标签归档:datetime

Delorean 优秀的Python时间格式转换工具

DeLorean是一个Python的第三方模块,基于 pytz 和 dateutil 开发的,用于处理Python中日期时间的格式转换。

由于时间转换是一个足够微妙的问题,DeLorean希望为移位、操作和生成日期时间提供一种更干净、更省事的解决方案。比如,实例化字符串形式的时间对象,Delorean只需要 parse 指定字符串,不需要声明其格式就可以进行转换。

至于 Delorean 这个模块名称的由来,Delorean 是电影《回到未来》里的那辆极为炫酷的鸥翼汽车,采用这部电影里的非常具有代表性的汽车的名字作为库名,作者估计也是想表达使用这个库能让你在时空里任意遨游,没有掣肘。

1.准备

开始之前,你要确保Python和pip已经成功安装在电脑上,如果没有,请访问这篇文章:超详细Python安装指南 进行安装。

(可选1) 如果你用Python的目的是数据分析,可以直接安装Anaconda:Python数据分析与挖掘好帮手—Anaconda,它内置了Python和pip.

(可选2) 此外,推荐大家用VSCode编辑器来编写小型Python项目:Python 编程的最好搭档—VSCode 详细指南

Windows环境下打开Cmd(开始—运行—CMD),苹果系统环境下请打开Terminal(command+空格输入Terminal),输入命令安装依赖:

pip install Delorean

2.Delorean 基础使用

轻松获取当前时间:

from delorean import Delorean

d = Delorean()
print(d)
# Delorean(datetime=datetime.datetime(2021, 10, 6, 9, 5, 57, 611589), timezone='UTC')

将datetime格式的时间转化为Delorean:

import datetime
from delorean import Delorean

d = Delorean()
print(d)
d = Delorean(datetime=datetime.datetime(2018, 5, 10, 8, 52, 23, 560811), timezone='UTC')
# 这里默认的是UTC时间
print(d)
# Delorean(datetime=datetime.datetime(2021, 10, 6, 9, 5, 57, 611589), timezone='UTC')
# Delorean(datetime=datetime.datetime(2018, 5, 10, 8, 52, 23, 560811), timezone='UTC')

转换为国内时区:

import datetime
from delorean import Delorean

d = Delorean(datetime=datetime.datetime(2018, 5, 10, 8, 52, 23, 560811), timezone='UTC')
d = d.shift("Asia/Shanghai")
print(d)
# Delorean(datetime=datetime.datetime(2018, 5, 10, 16, 52, 23, 560811), timezone='Asia/Shanghai')

输出为 datetime、date 也不在话下:

import datetime
from delorean import Delorean

d = Delorean(datetime=datetime.datetime(2018, 5, 10, 8, 52, 23, 560811), timezone='UTC')
d = d.shift("Asia/Shanghai")
print(d.datetime)
print(d.date)
# 2018-05-10 16:52:23.560811+08:00
# 2018-05-10

查看无时区时间及时间戳:

import datetime
from delorean import Delorean

d = Delorean(datetime=datetime.datetime(2018, 5, 10, 8, 52, 23, 560811), timezone='UTC')
d = d.shift("Asia/Shanghai")
print(d.epoch)
print(d.naive)
# 1525942343.560811
# 2018-05-10 08:52:23.560811

用unix时间戳初始化Delorean:

from delorean import epoch
d = epoch(1357971038.102223).shift("Asia/Shanghai")
print(d)
# Delorean(datetime=datetime.datetime(2013, 1, 12, 14, 10, 38, 102223), timezone='Asia/Shanghai')

Delorean支持timedelta的时间加减法。Delorean可以使用timedelta进行加减,得到一个Delorean对象:

import datetime
from delorean import Delorean

d = Delorean(datetime=datetime.datetime(2018, 5, 10, 8, 52, 23, 560811), timezone='UTC')
d = d.shift("Asia/Shanghai")
print(d)
d2 = d + datetime.timedelta(hours=2)
print(d2)
d3 = d - datetime.timedelta(hours=3)
print(d3)
# Delorean(datetime=datetime.datetime(2018, 5, 10, 16, 52, 23, 560811), timezone='Asia/Shanghai')
# Delorean(datetime=datetime.datetime(2018, 5, 10, 18, 52, 23, 560811), timezone='Asia/Shanghai')
# Delorean(datetime=datetime.datetime(2018, 5, 10, 13, 52, 23, 560811), timezone='Asia/Shanghai')

3. Delorean 高级使用

通常情况下我们不关心有多少微妙或者多少秒,因此Delorean提供了非常方便的过滤方式:

from delorean import Delorean

d = Delorean()
print(d)
# Delorean(datetime=datetime.datetime(2019, 3, 14, 4, 0, 50, 597357), timezone='UTC')
d.truncate('second')
# Delorean(datetime=datetime.datetime(2019, 3, 14, 4, 0, 50), timezone='UTC')
d.truncate('hour')
# Delorean(datetime=datetime.datetime(2019, 3, 14, 4, 0), timezone='UTC')
d.truncate('month')
# Delorean(datetime=datetime.datetime(2019, 3, 1, 0, 0), timezone='UTC')
d.truncate('year')
# Delorean(datetime=datetime.datetime(2019, 1, 1, 0, 0), timezone='UTC')

另外,datetime格式的字符串处理的时候转换需要标明各种各样的格式,在Delorean你直接parse就可以了:

from delorean import parse
parse("2011/01/01 00:00:00 -0700")
# Delorean(datetime=datetime.datetime(2011, 1, 1, 0, 0), timezone=pytz.FixedOffset(-420))
parse("2018-05-06")
# Delorean(datetime=datetime.datetime(2018, 6, 5, 0, 0), timezone='UTC')

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Python datetime-在使用strptime获取日,月,年之后设置固定的小时和分钟

问题:Python datetime-在使用strptime获取日,月,年之后设置固定的小时和分钟

我已经成功地将26 Sep 2012格式转换为26-09-2012使用:

datetime.strptime(request.POST['sample_date'],'%d %b %Y')

但是,我不知道如何将上述时间设置为11:59。有谁知道如何做到这一点?

请注意,这可以是将来的日期,也可以是任何随机的日期,而不仅仅是当前日期。

I’ve successfully converted something of 26 Sep 2012 format to 26-09-2012 using:

datetime.strptime(request.POST['sample_date'],'%d %b %Y')

However, I don’t know how to set the hour and minute of something like the above to 11:59. Does anyone know how to do this?

Note, this can be a future date or any random one, not just the current date.


回答 0

用途datetime.replace

from datetime import datetime
date = datetime.strptime('26 Sep 2012', '%d %b %Y')
newdate = date.replace(hour=11, minute=59)

Use datetime.replace:

from datetime import datetime
date = datetime.strptime('26 Sep 2012', '%d %b %Y')
newdate = date.replace(hour=11, minute=59)

回答 1

datetime.replace()将提供最佳选择。此外,它还提供了替换日,年和月的工具。

假设我们有一个datetime对象,日期表示为: "2017-05-04"

>>> from datetime import datetime
>>> date = datetime.strptime('2017-05-04',"%Y-%m-%d")
>>> print(date)
2017-05-04 00:00:00
>>> date = date.replace(minute=59, hour=23, second=59, year=2018, month=6, day=1)
>>> print(date)
2018-06-01 23:59:59

datetime.replace() will provide the best options. Also, it provides facility for replacing day, year, and month.

Suppose we have a datetime object and date is represented as: "2017-05-04"

>>> from datetime import datetime
>>> date = datetime.strptime('2017-05-04',"%Y-%m-%d")
>>> print(date)
2017-05-04 00:00:00
>>> date = date.replace(minute=59, hour=23, second=59, year=2018, month=6, day=1)
>>> print(date)
2018-06-01 23:59:59

如何在Django中过滤DateTimeField的日期?

问题:如何在Django中过滤DateTimeField的日期?

我试图过滤DateTimeField与日期比较。我的意思是:

MyObject.objects.filter(datetime_attr=datetime.date(2009,8,22))

我得到一个空的查询集列表作为答案,因为(我认为)我不在考虑时间,但我希望“任何时间”。

Django中有一种简单的方法吗?

我在datetime中设置了时间,但不是00:00

I am trying to filter a DateTimeField comparing with a date. I mean:

MyObject.objects.filter(datetime_attr=datetime.date(2009,8,22))

I get an empty queryset list as an answer because (I think) I am not considering time, but I want “any time”.

Is there an easy way in Django for doing this?

I have the time in the datetime setted, it is not 00:00.


回答 0

此类查询的实现django.views.generic.date_based方式如下:

{'date_time_field__range': (datetime.datetime.combine(date, datetime.time.min),
                            datetime.datetime.combine(date, datetime.time.max))} 

因为它很冗长,所以有计划使用__date运算符来改进语法。有关更多详细信息,请检查“ #9596将DateTimeField与日期比较太难 ”。

Such lookups are implemented in django.views.generic.date_based as follows:

{'date_time_field__range': (datetime.datetime.combine(date, datetime.time.min),
                            datetime.datetime.combine(date, datetime.time.max))} 

Because it is quite verbose there are plans to improve the syntax using __date operator. Check “#9596 Comparing a DateTimeField to a date is too hard” for more details.


回答 1

YourModel.objects.filter(datetime_published__year='2008', 
                         datetime_published__month='03', 
                         datetime_published__day='27')

//在评论后编辑

YourModel.objects.filter(datetime_published=datetime(2008, 03, 27))

不起作用,因为它创建了一个时间值设置为0的datetime对象,因此数据库中的时间不匹配。

YourModel.objects.filter(datetime_published__year='2008', 
                         datetime_published__month='03', 
                         datetime_published__day='27')

// edit after comments

YourModel.objects.filter(datetime_published=datetime(2008, 03, 27))

doest not work because it creates a datetime object with time values set to 0, so the time in database doesn’t match.


回答 2

这是我使用ipython的timeit函数得到的结果:

from datetime import date
today = date.today()

timeit[Model.objects.filter(date_created__year=today.year, date_created__month=today.month, date_created__day=today.day)]
1000 loops, best of 3: 652 us per loop

timeit[Model.objects.filter(date_created__gte=today)]
1000 loops, best of 3: 631 us per loop

timeit[Model.objects.filter(date_created__startswith=today)]
1000 loops, best of 3: 541 us per loop

timeit[Model.objects.filter(date_created__contains=today)]
1000 loops, best of 3: 536 us per loop

包含似乎更快。

Here are the results I got with ipython’s timeit function:

from datetime import date
today = date.today()

timeit[Model.objects.filter(date_created__year=today.year, date_created__month=today.month, date_created__day=today.day)]
1000 loops, best of 3: 652 us per loop

timeit[Model.objects.filter(date_created__gte=today)]
1000 loops, best of 3: 631 us per loop

timeit[Model.objects.filter(date_created__startswith=today)]
1000 loops, best of 3: 541 us per loop

timeit[Model.objects.filter(date_created__contains=today)]
1000 loops, best of 3: 536 us per loop

contains seems to be faster.


回答 3

现在,Django具有__date queryset过滤器,可以针对开发版本中的日期查询datetime对象。因此,它将很快在1.9中可用。

Now Django has __date queryset filter to query datetime objects against dates in development version. Thus, it will be available in 1.9 soon.


回答 4

Mymodel.objects.filter(date_time_field__contains=datetime.date(1986, 7, 28))

以上是我用过的。它不仅有效,而且还具有一些固有的逻辑支持。

Mymodel.objects.filter(date_time_field__contains=datetime.date(1986, 7, 28))

the above is what I’ve used. Not only does it work, it also has some inherent logical backing.


回答 5

从Django 1.9开始,执行此操作的方法是__date在datetime对象上使用。

例如: MyObject.objects.filter(datetime_attr__date=datetime.date(2009,8,22))

As of Django 1.9, the way to do this is by using __date on a datetime object.

For example: MyObject.objects.filter(datetime_attr__date=datetime.date(2009,8,22))


回答 6

这产生与使用__year,__ month和__day相同的结果,并且似乎对我有用:

YourModel.objects.filter(your_datetime_field__startswith=datetime.date(2009,8,22))

This produces the same results as using __year, __month, and __day and seems to work for me:

YourModel.objects.filter(your_datetime_field__startswith=datetime.date(2009,8,22))

回答 7

假设active_on是一个日期对象,将其增加1天,然后进行范围调整

next_day = active_on + datetime.timedelta(1)
queryset = queryset.filter(date_created__range=(active_on, next_day) )

assuming active_on is a date object, increment it by 1 day then do range

next_day = active_on + datetime.timedelta(1)
queryset = queryset.filter(date_created__range=(active_on, next_day) )

回答 8

这是一种有趣的技术-我利用在Django上在MySQL上实现的startswith过程来实现只在日期中查找日期时间的结果。基本上,当Django在数据库中进行查找时,它必须对DATETIME MySQL存储对象进行字符串转换,因此您可以对此进行过滤,而忽略日期的时间戳部分-这样%LIKE%仅与日期匹配对象,您将获得给定日期的每个时间戳。

datetime_filter = datetime(2009, 8, 22) 
MyObject.objects.filter(datetime_attr__startswith=datetime_filter.date())

这将执行以下查询:

SELECT (values) FROM myapp_my_object \ 
WHERE myapp_my_object.datetime_attr LIKE BINARY 2009-08-22%

在这种情况下,无论时间戳如何,LIKE BINARY都将匹配日期中的所有内容。包括以下值:

+---------------------+
| datetime_attr       |
+---------------------+
| 2009-08-22 11:05:08 |
+---------------------+

希望这对所有人都有帮助,直到Django提出解决方案为止!

Here is an interesting technique– I leveraged the startswith procedure as implemented with Django on MySQL to achieve the result of only looking up a datetime through only the date. Basically, when Django does the lookup in the database it has to do a string conversion for the DATETIME MySQL storage object, so you can filter on that, leaving out the timestamp portion of the date– that way %LIKE% matches only the date object and you’ll get every timestamp for the given date.

datetime_filter = datetime(2009, 8, 22) 
MyObject.objects.filter(datetime_attr__startswith=datetime_filter.date())

This will perform the following query:

SELECT (values) FROM myapp_my_object \ 
WHERE myapp_my_object.datetime_attr LIKE BINARY 2009-08-22%

The LIKE BINARY in this case will match everything for the date, no matter the timestamp. Including values like:

+---------------------+
| datetime_attr       |
+---------------------+
| 2009-08-22 11:05:08 |
+---------------------+

Hopefully this helps everyone until Django comes out with a solution!


回答 9

这里有一篇很棒的博客文章:在Django ORM中比较日期和日期时间

为Django> 1.7,<1.9发布的最佳解决方案是注册一个转换:

from django.db import models

class MySQLDatetimeDate(models.Transform):
    """
    This implements a custom SQL lookup when using `__date` with datetimes.
    To enable filtering on datetimes that fall on a given date, import
    this transform and register it with the DateTimeField.
    """
    lookup_name = 'date'

    def as_sql(self, compiler, connection):
        lhs, params = compiler.compile(self.lhs)
        return 'DATE({})'.format(lhs), params

    @property
    def output_field(self):
        return models.DateField()

然后可以在过滤器中使用它,如下所示:

Foo.objects.filter(created_on__date=date)

编辑

此解决方案绝对取决于后端。从文章:

当然,此实现依赖于具有DATE()函数的SQL的特定风格。MySQL确实如此。SQLite也是如此。另一方面,我还没有亲自使用PostgreSQL,但是通过谷歌搜索使我相信它没有DATE()函数。因此,这种简单的实现似乎必然与后端有关。

There’s a fantastic blogpost that covers this here: Comparing Dates and Datetimes in the Django ORM

The best solution posted for Django>1.7,<1.9 is to register a transform:

from django.db import models

class MySQLDatetimeDate(models.Transform):
    """
    This implements a custom SQL lookup when using `__date` with datetimes.
    To enable filtering on datetimes that fall on a given date, import
    this transform and register it with the DateTimeField.
    """
    lookup_name = 'date'

    def as_sql(self, compiler, connection):
        lhs, params = compiler.compile(self.lhs)
        return 'DATE({})'.format(lhs), params

    @property
    def output_field(self):
        return models.DateField()

Then you can use it in your filters like this:

Foo.objects.filter(created_on__date=date)

EDIT

This solution is definitely back end dependent. From the article:

Of course, this implementation relies on your particular flavor of SQL having a DATE() function. MySQL does. So does SQLite. On the other hand, I haven’t worked with PostgreSQL personally, but some googling leads me to believe that it does not have a DATE() function. So an implementation this simple seems like it will necessarily be somewhat backend-dependent.


回答 10

嗯..我的解决方案正在工作:

Mymodel.objects.filter(date_time_field__startswith=datetime.datetime(1986, 7, 28))

Hm.. My solution is working:

Mymodel.objects.filter(date_time_field__startswith=datetime.datetime(1986, 7, 28))

回答 11

Model.objects.filter(datetime__year=2011, datetime__month=2, datetime__day=30)
Model.objects.filter(datetime__year=2011, datetime__month=2, datetime__day=30)

回答 12

在Django 1.7.6中工作:

MyObject.objects.filter(datetime_attr__startswith=datetime.date(2009,8,22))

In Django 1.7.6 works:

MyObject.objects.filter(datetime_attr__startswith=datetime.date(2009,8,22))

回答 13

请参阅文章Django文档

ur_data_model.objects.filter(ur_date_field__gte=datetime(2009, 8, 22), ur_date_field__lt=datetime(2009, 8, 23))

See the article Django Documentation

ur_data_model.objects.filter(ur_date_field__gte=datetime(2009, 8, 22), ur_date_field__lt=datetime(2009, 8, 23))

如何将python datetime转换为具有可读格式date的字符串?

问题:如何将python datetime转换为具有可读格式date的字符串?

t = e['updated_parsed']
dt = datetime.datetime(t[0],t[1],t[2],t[3],t[4],t[5],t[6]
print dt
>>>2010-01-28 08:39:49.000003

如何将其转换为字符串?:

"January 28, 2010"
t = e['updated_parsed']
dt = datetime.datetime(t[0],t[1],t[2],t[3],t[4],t[5],t[6]
print dt
>>>2010-01-28 08:39:49.000003

How do I turn that into a string?:

"January 28, 2010"

回答 0

datetime类具有strftime方法。Python文档记录了它接受的不同格式:

对于此特定示例,它将类似于:

my_datetime.strftime("%B %d, %Y")

The datetime class has a method strftime. The Python docs documents the different formats it accepts:

For this specific example, it would look something like:

my_datetime.strftime("%B %d, %Y")

回答 1

这是您可以使用python的常规格式化功能来完成的操作…

>>>from datetime import datetime
>>>"{:%B %d, %Y}".format(datetime.now())

此处使用的格式字符与strftime所使用的格式字符相同。不要错过: 格式说明符的开头。

在大多数情况下,使用format()代替strftime()可以使代码更具可读性,易于编写,并且与格式化输出的生成方式保持一致…

>>>"{} today's date is: {:%B %d, %Y}".format("Andre", datetime.now())

将以上内容与以下strftime()替代项进行比较…

>>>"{} today's date is {}".format("Andre", datetime.now().strftime("%B %d, %Y"))

此外,以下内容将无法工作…

>>>datetime.now().strftime("%s %B %d, %Y" % "Andre")
Traceback (most recent call last):
  File "<pyshell#11>", line 1, in <module>
    datetime.now().strftime("%s %B %d, %Y" % "Andre")
TypeError: not enough arguments for format string

等等…

Here is how you can accomplish the same using python’s general formatting function…

>>>from datetime import datetime
>>>"{:%B %d, %Y}".format(datetime.now())

The formatting characters used here are the same as those used by strftime. Don’t miss the leading : in the format specifier.

Using format() instead of strftime() in most cases can make the code more readable, easier to write and consistent with the way formatted output is generated…

>>>"{} today's date is: {:%B %d, %Y}".format("Andre", datetime.now())

Compare the above with the following strftime() alternative…

>>>"{} today's date is {}".format("Andre", datetime.now().strftime("%B %d, %Y"))

Moreover, the following is not going to work…

>>>datetime.now().strftime("%s %B %d, %Y" % "Andre")
Traceback (most recent call last):
  File "<pyshell#11>", line 1, in <module>
    datetime.now().strftime("%s %B %d, %Y" % "Andre")
TypeError: not enough arguments for format string

And so on…


回答 2

在Python 3.6及更高版本中使用f字符串。

from datetime import datetime

date_string = f'{datetime.now():%Y-%m-%d %H:%M:%S%z}'

Using f-strings, in Python 3.6+.

from datetime import datetime

date_string = f'{datetime.now():%Y-%m-%d %H:%M:%S%z}'

回答 3

我知道很老的问题。但是有了新的f字符串(从python 3.6开始),就有了新的选择。所以这里是为了完整性:

from datetime import datetime

dt = datetime.now()

# str.format
strg = '{:%B %d, %Y}'.format(dt)
print(strg)  # July 22, 2017

# datetime.strftime
strg = dt.strftime('%B %d, %Y')
print(strg)  # July 22, 2017

# f-strings in python >= 3.6
strg = f'{dt:%B %d, %Y}'
print(strg)  # July 22, 2017

strftime()and strptime()Behavior解释格式说明符的含义。

very old question, i know. but with the new f-strings (starting from python 3.6) there are fresh options. so here for completeness:

from datetime import datetime

dt = datetime.now()

# str.format
strg = '{:%B %d, %Y}'.format(dt)
print(strg)  # July 22, 2017

# datetime.strftime
strg = dt.strftime('%B %d, %Y')
print(strg)  # July 22, 2017

# f-strings in python >= 3.6
strg = f'{dt:%B %d, %Y}'
print(strg)  # July 22, 2017

strftime() and strptime() Behavior explains what the format specifiers mean.


回答 4

阅读官方文档中的strfrtime

Read strfrtime from the official docs.


回答 5

Python datetime对象具有method属性,该属性以可读格式打印。

>>> a = datetime.now()
>>> a.ctime()
'Mon May 21 18:35:18 2018'
>>> 

Python datetime object has a method attribute, which prints in readable format.

>>> a = datetime.now()
>>> a.ctime()
'Mon May 21 18:35:18 2018'
>>> 

回答 6

这是用于格式化的日期吗?

def format_date(day, month, year):
        # {} betekent 'plaats hier stringvoorstelling van volgend argument'
        return "{}/{}/{}".format(day, month, year)

This is for format the date?

def format_date(day, month, year):
        # {} betekent 'plaats hier stringvoorstelling van volgend argument'
        return "{}/{}/{}".format(day, month, year)

在其他两个日期之间生成一个随机日期

问题:在其他两个日期之间生成一个随机日期

如何生成必须在其他两个给定日期之间的随机日期?

该函数的签名应如下所示:

random_date("1/1/2008 1:30 PM", "1/1/2009 4:50 AM", 0.34)
                   ^                       ^          ^

            date generated has  date generated has  a random number
            to be after this    to be before this

并返回一个日期,例如: 2/4/2008 7:20 PM

How would I generate a random date that has to be between two other given dates?

The function’s signature should be something like this:

random_date("1/1/2008 1:30 PM", "1/1/2009 4:50 AM", 0.34)
                   ^                       ^          ^

            date generated has  date generated has  a random number
            to be after this    to be before this

and would return a date such as: 2/4/2008 7:20 PM


回答 0

将两个字符串都转换为时间戳(以您选择的分辨率为单位,例如毫秒,秒,小时,天等),从后一个减去前一个,将您的随机数(假设分布在中range [0, 1])乘以该差,然后再次加较早的一个。将时间戳转换回日期字符串,并且您在该范围内有一个随机时间。

Python示例(输出几乎是您指定的格式,而不是0填充-归咎于美国时间格式约定):

import random
import time

def str_time_prop(start, end, format, prop):
    """Get a time at a proportion of a range of two formatted times.

    start and end should be strings specifying times formated in the
    given format (strftime-style), giving an interval [start, end].
    prop specifies how a proportion of the interval to be taken after
    start.  The returned time will be in the specified format.
    """

    stime = time.mktime(time.strptime(start, format))
    etime = time.mktime(time.strptime(end, format))

    ptime = stime + prop * (etime - stime)

    return time.strftime(format, time.localtime(ptime))


def random_date(start, end, prop):
    return str_time_prop(start, end, '%m/%d/%Y %I:%M %p', prop)

print(random_date("1/1/2008 1:30 PM", "1/1/2009 4:50 AM", random.random()))

Convert both strings to timestamps (in your chosen resolution, e.g. milliseconds, seconds, hours, days, whatever), subtract the earlier from the later, multiply your random number (assuming it is distributed in the range [0, 1]) with that difference, and add again to the earlier one. Convert the timestamp back to date string and you have a random time in that range.

Python example (output is almost in the format you specified, other than 0 padding – blame the American time format conventions):

import random
import time

def str_time_prop(start, end, format, prop):
    """Get a time at a proportion of a range of two formatted times.

    start and end should be strings specifying times formated in the
    given format (strftime-style), giving an interval [start, end].
    prop specifies how a proportion of the interval to be taken after
    start.  The returned time will be in the specified format.
    """

    stime = time.mktime(time.strptime(start, format))
    etime = time.mktime(time.strptime(end, format))

    ptime = stime + prop * (etime - stime)

    return time.strftime(format, time.localtime(ptime))


def random_date(start, end, prop):
    return str_time_prop(start, end, '%m/%d/%Y %I:%M %p', prop)

print(random_date("1/1/2008 1:30 PM", "1/1/2009 4:50 AM", random.random()))

回答 1

from random import randrange
from datetime import timedelta

def random_date(start, end):
    """
    This function will return a random datetime between two datetime 
    objects.
    """
    delta = end - start
    int_delta = (delta.days * 24 * 60 * 60) + delta.seconds
    random_second = randrange(int_delta)
    return start + timedelta(seconds=random_second)

精度是秒。如果需要,您可以将精度提高到微秒,或降低到半小时。为此,只需更改最后一行的计算即可。

示例运行:

from datetime import datetime

d1 = datetime.strptime('1/1/2008 1:30 PM', '%m/%d/%Y %I:%M %p')
d2 = datetime.strptime('1/1/2009 4:50 AM', '%m/%d/%Y %I:%M %p')

print(random_date(d1, d2))

输出:

2008-12-04 01:50:17
from random import randrange
from datetime import timedelta

def random_date(start, end):
    """
    This function will return a random datetime between two datetime 
    objects.
    """
    delta = end - start
    int_delta = (delta.days * 24 * 60 * 60) + delta.seconds
    random_second = randrange(int_delta)
    return start + timedelta(seconds=random_second)

The precision is seconds. You can increase precision up to microseconds, or decrease to, say, half-hours, if you want. For that just change the last line’s calculation.

example run:

from datetime import datetime

d1 = datetime.strptime('1/1/2008 1:30 PM', '%m/%d/%Y %I:%M %p')
d2 = datetime.strptime('1/1/2009 4:50 AM', '%m/%d/%Y %I:%M %p')

print(random_date(d1, d2))

output:

2008-12-04 01:50:17

回答 2

一个小版本。

import datetime
import random


def random_date(start, end):
    """Generate a random datetime between `start` and `end`"""
    return start + datetime.timedelta(
        # Get a random amount of seconds between `start` and `end`
        seconds=random.randint(0, int((end - start).total_seconds())),
    )

请注意,startend参数都应该是datetime对象。如果您有字符串,则很容易转换。其他答案指出了这样做的一些方法。

A tiny version.

import datetime
import random


def random_date(start, end):
    """Generate a random datetime between `start` and `end`"""
    return start + datetime.timedelta(
        # Get a random amount of seconds between `start` and `end`
        seconds=random.randint(0, int((end - start).total_seconds())),
    )

Note that both start and end arguments should be datetime objects. If you’ve got strings instead, it’s fairly easy to convert. The other answers point to some ways to do so.


回答 3

更新的答案

使用Faker甚至更简单。

安装

pip install faker

用法:

from faker import Faker
fake = Faker()

fake.date_between(start_date='today', end_date='+30y')
# datetime.date(2025, 3, 12)

fake.date_time_between(start_date='-30y', end_date='now')
# datetime.datetime(2007, 2, 28, 11, 28, 16)

# Or if you need a more specific date boundaries, provide the start 
# and end dates explicitly.
import datetime
start_date = datetime.date(year=2015, month=1, day=1)
fake.date_between(start_date=start_date, end_date='+30y')

旧答案

使用雷达非常简单

安装

pip install radar

用法

import datetime

import radar 

# Generate random datetime (parsing dates from str values)
radar.random_datetime(start='2000-05-24', stop='2013-05-24T23:59:59')

# Generate random datetime from datetime.datetime values
radar.random_datetime(
    start = datetime.datetime(year=2000, month=5, day=24),
    stop = datetime.datetime(year=2013, month=5, day=24)
)

# Just render some random datetime. If no range is given, start defaults to 
# 1970-01-01 and stop defaults to datetime.datetime.now()
radar.random_datetime()

Updated answer

It’s even more simple using Faker.

Installation

pip install faker

Usage:

from faker import Faker
fake = Faker()

fake.date_between(start_date='today', end_date='+30y')
# datetime.date(2025, 3, 12)

fake.date_time_between(start_date='-30y', end_date='now')
# datetime.datetime(2007, 2, 28, 11, 28, 16)

# Or if you need a more specific date boundaries, provide the start 
# and end dates explicitly.
import datetime
start_date = datetime.date(year=2015, month=1, day=1)
fake.date_between(start_date=start_date, end_date='+30y')

Old answer

It’s very simple using radar

Installation

pip install radar

Usage

import datetime

import radar 

# Generate random datetime (parsing dates from str values)
radar.random_datetime(start='2000-05-24', stop='2013-05-24T23:59:59')

# Generate random datetime from datetime.datetime values
radar.random_datetime(
    start = datetime.datetime(year=2000, month=5, day=24),
    stop = datetime.datetime(year=2013, month=5, day=24)
)

# Just render some random datetime. If no range is given, start defaults to 
# 1970-01-01 and stop defaults to datetime.datetime.now()
radar.random_datetime()

回答 4

这是另一种方法-这种工作。

from random import randint
import datetime

date=datetime.date(randint(2005,2025), randint(1,12),randint(1,28))

更好的方法

startdate=datetime.date(YYYY,MM,DD)
date=startdate+datetime.timedelta(randint(1,365))

This is a different approach – that sort of works..

from random import randint
import datetime

date=datetime.date(randint(2005,2025), randint(1,12),randint(1,28))

BETTER APPROACH

startdate=datetime.date(YYYY,MM,DD)
date=startdate+datetime.timedelta(randint(1,365))

回答 5

由于Python 3 timedelta支持浮点数乘法,因此现在您可以执行以下操作:

import random
random_date = start + (end - start) * random.random()

鉴于startend是类型的datetime.datetime。例如,要在第二天生成一个随机的日期时间:

import random
from datetime import datetime, timedelta

start = datetime.now()
end = start + timedelta(days=1)
random_date = start + (end - start) * random.random()

Since Python 3 timedelta supports multiplication with floats, so now you can do:

import random
random_date = start + (end - start) * random.random()

given that start and end are of the type datetime.datetime. For example, to generate a random datetime within the next day:

import random
from datetime import datetime, timedelta

start = datetime.now()
end = start + timedelta(days=1)
random_date = start + (end - start) * random.random()

回答 6

要使用基于熊猫的解决方案,我使用:

import pandas as pd
import numpy as np

def random_date(start, end, position=None):
    start, end = pd.Timestamp(start), pd.Timestamp(end)
    delta = (end - start).total_seconds()
    if position is None:
        offset = np.random.uniform(0., delta)
    else:
        offset = position * delta
    offset = pd.offsets.Second(offset)
    t = start + offset
    return t

我喜欢它,因为很好 pd.Timestamp出色功能使我可以抛出不同的内容和格式。考虑以下几个示例…

你的签名。

>>> random_date(start="1/1/2008 1:30 PM", end="1/1/2009 4:50 AM", position=0.34)
Timestamp('2008-05-04 21:06:48', tz=None)

随机位置。

>>> random_date(start="1/1/2008 1:30 PM", end="1/1/2009 4:50 AM")
Timestamp('2008-10-21 05:30:10', tz=None)

不同的格式。

>>> random_date('2008-01-01 13:30', '2009-01-01 4:50')
Timestamp('2008-11-18 17:20:19', tz=None)

直接传递熊猫/日期时间对象。

>>> random_date(pd.datetime.now(), pd.datetime.now() + pd.offsets.Hour(3))
Timestamp('2014-03-06 14:51:16.035965', tz=None)

To chip in a pandas-based solution I use:

import pandas as pd
import numpy as np

def random_date(start, end, position=None):
    start, end = pd.Timestamp(start), pd.Timestamp(end)
    delta = (end - start).total_seconds()
    if position is None:
        offset = np.random.uniform(0., delta)
    else:
        offset = position * delta
    offset = pd.offsets.Second(offset)
    t = start + offset
    return t

I like it, because of the nice pd.Timestamp features that allow me to throw different stuff and formats at it. Consider the following few examples…

Your signature.

>>> random_date(start="1/1/2008 1:30 PM", end="1/1/2009 4:50 AM", position=0.34)
Timestamp('2008-05-04 21:06:48', tz=None)

Random position.

>>> random_date(start="1/1/2008 1:30 PM", end="1/1/2009 4:50 AM")
Timestamp('2008-10-21 05:30:10', tz=None)

Different format.

>>> random_date('2008-01-01 13:30', '2009-01-01 4:50')
Timestamp('2008-11-18 17:20:19', tz=None)

Passing pandas/datetime objects directly.

>>> random_date(pd.datetime.now(), pd.datetime.now() + pd.offsets.Hour(3))
Timestamp('2014-03-06 14:51:16.035965', tz=None)

回答 7

这是标题标题的字面意思的答案,而不是问题的正文:

import time
import datetime
import random

def date_to_timestamp(d) :
  return int(time.mktime(d.timetuple()))

def randomDate(start, end):
  """Get a random date between two dates"""

  stime = date_to_timestamp(start)
  etime = date_to_timestamp(end)

  ptime = stime + random.random() * (etime - stime)

  return datetime.date.fromtimestamp(ptime)

这段代码大致基于公认的答案。

Here is an answer to the literal meaning of the title rather than the body of this question:

import time
import datetime
import random

def date_to_timestamp(d) :
  return int(time.mktime(d.timetuple()))

def randomDate(start, end):
  """Get a random date between two dates"""

  stime = date_to_timestamp(start)
  etime = date_to_timestamp(end)

  ptime = stime + random.random() * (etime - stime)

  return datetime.date.fromtimestamp(ptime)

This code is based loosely on the accepted answer.


回答 8

您可以使用Mixer

pip install mixer

和,

from mixer import generators as gen
print gen.get_datetime(min_datetime=(1900, 1, 1, 0, 0, 0), max_datetime=(2020, 12, 31, 23, 59, 59))

You can Use Mixer,

pip install mixer

and,

from mixer import generators as gen
print gen.get_datetime(min_datetime=(1900, 1, 1, 0, 0, 0), max_datetime=(2020, 12, 31, 23, 59, 59))

回答 9

#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""Create random datetime object."""

from datetime import datetime
import random


def create_random_datetime(from_date, to_date, rand_type='uniform'):
    """
    Create random date within timeframe.

    Parameters
    ----------
    from_date : datetime object
    to_date : datetime object
    rand_type : {'uniform'}

    Examples
    --------
    >>> random.seed(28041990)
    >>> create_random_datetime(datetime(1990, 4, 28), datetime(2000, 12, 31))
    datetime.datetime(1998, 12, 13, 23, 38, 0, 121628)
    >>> create_random_datetime(datetime(1990, 4, 28), datetime(2000, 12, 31))
    datetime.datetime(2000, 3, 19, 19, 24, 31, 193940)
    """
    delta = to_date - from_date
    if rand_type == 'uniform':
        rand = random.random()
    else:
        raise NotImplementedError('Unknown random mode \'{}\''
                                  .format(rand_type))
    return from_date + rand * delta


if __name__ == '__main__':
    import doctest
    doctest.testmod()
#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""Create random datetime object."""

from datetime import datetime
import random


def create_random_datetime(from_date, to_date, rand_type='uniform'):
    """
    Create random date within timeframe.

    Parameters
    ----------
    from_date : datetime object
    to_date : datetime object
    rand_type : {'uniform'}

    Examples
    --------
    >>> random.seed(28041990)
    >>> create_random_datetime(datetime(1990, 4, 28), datetime(2000, 12, 31))
    datetime.datetime(1998, 12, 13, 23, 38, 0, 121628)
    >>> create_random_datetime(datetime(1990, 4, 28), datetime(2000, 12, 31))
    datetime.datetime(2000, 3, 19, 19, 24, 31, 193940)
    """
    delta = to_date - from_date
    if rand_type == 'uniform':
        rand = random.random()
    else:
        raise NotImplementedError('Unknown random mode \'{}\''
                                  .format(rand_type))
    return from_date + rand * delta


if __name__ == '__main__':
    import doctest
    doctest.testmod()

回答 10

将您的日期转换为时间戳并random.randint使用时间戳进行调用,然后将随机生成的时间戳转换回日期:

from datetime import datetime
import random

def random_date(first_date, second_date):
    first_timestamp = int(first_date.timestamp())
    second_timestamp = int(second_date.timestamp())
    random_timestamp = random.randint(first_timestamp, second_timestamp)
    return datetime.fromtimestamp(random_timestamp)

那你可以这样用

from datetime import datetime

d1 = datetime.strptime("1/1/2018 1:30 PM", "%m/%d/%Y %I:%M %p")
d2 = datetime.strptime("1/1/2019 4:50 AM", "%m/%d/%Y %I:%M %p")

random_date(d1, d2)

random_date(d2, d1)  # ValueError because the first date comes after the second date

如果您关心时区,则应该date_time_between_datesFaker库中使用它,因为我已经从中窃取了此代码,因为已经给出了另一个答案。

Convert your dates into timestamps and call random.randint with the timestamps, then convert the randomly generated timestamp back into a date:

from datetime import datetime
import random

def random_date(first_date, second_date):
    first_timestamp = int(first_date.timestamp())
    second_timestamp = int(second_date.timestamp())
    random_timestamp = random.randint(first_timestamp, second_timestamp)
    return datetime.fromtimestamp(random_timestamp)

Then you can use it like this

from datetime import datetime

d1 = datetime.strptime("1/1/2018 1:30 PM", "%m/%d/%Y %I:%M %p")
d2 = datetime.strptime("1/1/2019 4:50 AM", "%m/%d/%Y %I:%M %p")

random_date(d1, d2)

random_date(d2, d1)  # ValueError because the first date comes after the second date

If you care about timezones you should just use date_time_between_dates from the Faker library, where I stole this code from, as a different answer already suggests.


回答 11

  1. 将输入日期转换为数字(整数,浮点数,最适合您的用法)
  2. 在两个日期数字之间选择一个数字。
  3. 将此数字转换回日期。

许多操作系统中已经提供了许多用于将日期与数字进行日期转换的算法。

  1. Convert your input dates to numbers (int, float, whatever is best for your usage)
  2. Choose a number between your two date numbers.
  3. Convert this number back to a date.

Many algorithms for converting date to and from numbers are already available in many operating systems.


回答 12

您需要什么随机数?通常(取决于语言),您可以从日期开始获取到纪元的秒数​​/毫秒数。因此,对于startDate和endDate之间的随机日期,您可以执行以下操作:

  1. 以毫秒为单位计算startDate和endDate之间的时间(endDate.toMilliseconds()-startDate.toMilliseconds())
  2. 生成一个介于0和1之间的数字
  3. 生成一个新的Date,其时间偏移量= startDate.toMilliseconds()+ 2中获得的数字

What do you need the random number for? Usually (depending on the language) you can get the number of seconds/milliseconds from the Epoch from a date. So for a randomd date between startDate and endDate you could do:

  1. compute the time in ms between startDate and endDate (endDate.toMilliseconds() – startDate.toMilliseconds())
  2. generate a number between 0 and the number you obtained in 1
  3. generate a new Date with time offset = startDate.toMilliseconds() + number obtained in 2

回答 13

最简单的方法是将两个数字都转换为时间戳,然后将其设置为随机数生成器的最小和最大界限。

一个快速的PHP示例是:

// Find a randomDate between $start_date and $end_date
function randomDate($start_date, $end_date)
{
    // Convert to timetamps
    $min = strtotime($start_date);
    $max = strtotime($end_date);

    // Generate random number using above bounds
    $val = rand($min, $max);

    // Convert back to desired date format
    return date('Y-m-d H:i:s', $val);
}

此函数strtotime()用于将日期时间描述转换为Unix时间戳,并date()根据已生成的随机时间戳生成有效日期。

The easiest way of doing this is to convert both numbers to timestamps, then set these as the minimum and maximum bounds on a random number generator.

A quick PHP example would be:

// Find a randomDate between $start_date and $end_date
function randomDate($start_date, $end_date)
{
    // Convert to timetamps
    $min = strtotime($start_date);
    $max = strtotime($end_date);

    // Generate random number using above bounds
    $val = rand($min, $max);

    // Convert back to desired date format
    return date('Y-m-d H:i:s', $val);
}

This function makes use of strtotime() to convert a datetime description into a Unix timestamp, and date() to make a valid date out of the random timestamp which has been generated.


回答 14

只是添加另一个:

datestring = datetime.datetime.strftime(datetime.datetime( \
    random.randint(2000, 2015), \
    random.randint(1, 12), \
    random.randint(1, 28), \
    random.randrange(23), \
    random.randrange(59), \
    random.randrange(59), \
    random.randrange(1000000)), '%Y-%m-%d %H:%M:%S')

日常处理需要一些注意事项。28岁时,您就在安全的网站上。

Just to add another one:

datestring = datetime.datetime.strftime(datetime.datetime( \
    random.randint(2000, 2015), \
    random.randint(1, 12), \
    random.randint(1, 28), \
    random.randrange(23), \
    random.randrange(59), \
    random.randrange(59), \
    random.randrange(1000000)), '%Y-%m-%d %H:%M:%S')

The day handling needs some considerations. With 28 you are on the secure site.


回答 15

这是从emyller的方法修改而来的解决方案,该方法以任何分辨率返回随机日期数组

import numpy as np

def random_dates(start, end, size=1, resolution='s'):
    """
    Returns an array of random dates in the interval [start, end]. Valid 
    resolution arguments are numpy date/time units, as documented at: 
        https://docs.scipy.org/doc/numpy-dev/reference/arrays.datetime.html
    """
    start, end = np.datetime64(start), np.datetime64(end)
    delta = (end-start).astype('timedelta64[{}]'.format(resolution))
    delta_mat = np.random.randint(0, delta.astype('int'), size)
    return start + delta_mat.astype('timedelta64[{}]'.format(resolution))

这种方法的部分优点在于,np.datetime64它确实擅长将日期强制转换为日期,因此您可以将开始/结束日期指定为字符串,日期时间,熊猫时间戳记……几乎所有东西都可以使用。

Here’s a solution modified from emyller’s approach which returns an array of random dates at any resolution

import numpy as np

def random_dates(start, end, size=1, resolution='s'):
    """
    Returns an array of random dates in the interval [start, end]. Valid 
    resolution arguments are numpy date/time units, as documented at: 
        https://docs.scipy.org/doc/numpy-dev/reference/arrays.datetime.html
    """
    start, end = np.datetime64(start), np.datetime64(end)
    delta = (end-start).astype('timedelta64[{}]'.format(resolution))
    delta_mat = np.random.randint(0, delta.astype('int'), size)
    return start + delta_mat.astype('timedelta64[{}]'.format(resolution))

Part of what’s nice about this approach is that np.datetime64 is really good at coercing things to dates, so you can specify your start/end dates as strings, datetimes, pandas timestamps… pretty much anything will work.


回答 16

从概念上讲,这很简单。根据您所使用的语言,您将能够将这些日期转换为参考32或64位整数,通常表示自纪元(1970年1月1日)以来的秒数(否则称为“ Unix时间”)或自某个其他任意日期以来的毫秒数。只需在这两个值之间生成一个随机的32或64位整数。这应该是任何语言的统一班轮。

在某些平台上,您可以将时间生成为两倍(日期是整数部分,时间是小数部分是一种实现)。除了要处理单精度或双精度浮点数(在C,Java和其他语言中为“ floats”或“ doubles”)外,该原理均适用。减去差,乘以随机数(0 <= r <= 1),加到开始时间并完成。

Conceptually it’s quite simple. Depending on which language you’re using you will be able to convert those dates into some reference 32 or 64 bit integer, typically representing seconds since epoch (1 January 1970) otherwise known as “Unix time” or milliseconds since some other arbitrary date. Simply generate a random 32 or 64 bit integer between those two values. This should be a one liner in any language.

On some platforms you can generate a time as a double (date is the integer part, time is the fractional part is one implementation). The same principle applies except you’re dealing with single or double precision floating point numbers (“floats” or “doubles” in C, Java and other languages). Subtract the difference, multiply by random number (0 <= r <= 1), add to start time and done.


回答 17

在python中:

>>> from dateutil.rrule import rrule, DAILY
>>> import datetime, random
>>> random.choice(
                 list(
                     rrule(DAILY, 
                           dtstart=datetime.date(2009,8,21), 
                           until=datetime.date(2010,10,12))
                     )
                 )
datetime.datetime(2010, 2, 1, 0, 0)

(需要python dateutil库– pip install python-dateutil

In python:

>>> from dateutil.rrule import rrule, DAILY
>>> import datetime, random
>>> random.choice(
                 list(
                     rrule(DAILY, 
                           dtstart=datetime.date(2009,8,21), 
                           until=datetime.date(2010,10,12))
                     )
                 )
datetime.datetime(2010, 2, 1, 0, 0)

(need python dateutil library – pip install python-dateutil)


回答 18

使用ApacheCommonUtils生成给定范围内的随机长度,然后在该长度范围之外创建Date。

例:

导入org.apache.commons.math.random.RandomData;

导入org.apache.commons.math.random.RandomDataImpl;

公开日期nextDate(最小日期,最大日期){

RandomData randomData = new RandomDataImpl();

return new Date(randomData.nextLong(min.getTime(), max.getTime()));

}

Use ApacheCommonUtils to generate a random long within a given range, and then create Date out of that long.

Example:

import org.apache.commons.math.random.RandomData;

import org.apache.commons.math.random.RandomDataImpl;

public Date nextDate(Date min, Date max) {

RandomData randomData = new RandomDataImpl();

return new Date(randomData.nextLong(min.getTime(), max.getTime()));

}


回答 19

我用随机和时间为另一个项目做了这个。我从一开始就使用通用格式,您可以在此处查看strftime()中第一个参数的文档。第二部分是random.randrange函数。它在参数之间返回一个整数。将其更改为与您想要的字符串匹配的范围。在第二个扩展的元组中,您必须有很好的论据。

import time
import random


def get_random_date():
    return strftime("%Y-%m-%d %H:%M:%S",(random.randrange(2000,2016),random.randrange(1,12),
    random.randrange(1,28),random.randrange(1,24),random.randrange(1,60),random.randrange(1,60),random.randrange(1,7),random.randrange(0,366),1))

I made this for another project using random and time. I used a general format from time you can view the documentation here for the first argument in strftime(). The second part is a random.randrange function. It returns an integer between the arguments. Change it to the ranges that match the strings you would like. You must have nice arguments in the tuple of the second arugment.

import time
import random


def get_random_date():
    return strftime("%Y-%m-%d %H:%M:%S",(random.randrange(2000,2016),random.randrange(1,12),
    random.randrange(1,28),random.randrange(1,24),random.randrange(1,60),random.randrange(1,60),random.randrange(1,7),random.randrange(0,366),1))

回答 20

熊猫+ numpy解决方案

import pandas as pd
import numpy as np

def RandomTimestamp(start, end):
    dts = (end - start).total_seconds()
    return start + pd.Timedelta(np.random.uniform(0, dts), 's')

dts是时间戳之间的时间差(以秒为单位)(浮动)。然后将其用于创建介于0和dts之间的熊猫时间增量,并将其添加到开始时间戳中。

Pandas + numpy solution

import pandas as pd
import numpy as np

def RandomTimestamp(start, end):
    dts = (end - start).total_seconds()
    return start + pd.Timedelta(np.random.uniform(0, dts), 's')

dts is the difference between timestamps in seconds (float). It is then used to create a pandas timedelta between 0 and dts, that is added to the start timestamp.


回答 21

根据mouviciel的回答,这是使用numpy的矢量化解决方案。将开始日期和结束日期转换为整数,在它们之间生成一个随机数数组,然后将整个数组转换回日期。

import time
import datetime
import numpy as np

n_rows = 10

start_time = "01/12/2011"
end_time = "05/08/2017"

date2int = lambda s: time.mktime(datetime.datetime.strptime(s,"%d/%m/%Y").timetuple())
int2date = lambda s: datetime.datetime.fromtimestamp(s).strftime('%Y-%m-%d %H:%M:%S')

start_time = date2int(start_time)
end_time = date2int(end_time)

random_ints = np.random.randint(low=start_time, high=end_time, size=(n_rows,1))
random_dates = np.apply_along_axis(int2date, 1, random_ints).reshape(n_rows,1)

print random_dates

Based on the answer by mouviciel, here is a vectorized solution using numpy. Convert the start and end dates to ints, generate an array of random numbers between them, and convert the whole array back to dates.

import time
import datetime
import numpy as np

n_rows = 10

start_time = "01/12/2011"
end_time = "05/08/2017"

date2int = lambda s: time.mktime(datetime.datetime.strptime(s,"%d/%m/%Y").timetuple())
int2date = lambda s: datetime.datetime.fromtimestamp(s).strftime('%Y-%m-%d %H:%M:%S')

start_time = date2int(start_time)
end_time = date2int(end_time)

random_ints = np.random.randint(low=start_time, high=end_time, size=(n_rows,1))
random_dates = np.apply_along_axis(int2date, 1, random_ints).reshape(n_rows,1)

print random_dates

回答 22

它是@(Tom Alsberg)的修改方法。我将其修改为以毫秒为单位获取日期。

import random
import time
import datetime

def random_date(start_time_string, end_time_string, format_string, random_number):
    """
    Get a time at a proportion of a range of two formatted times.
    start and end should be strings specifying times formated in the
    given format (strftime-style), giving an interval [start, end].
    prop specifies how a proportion of the interval to be taken after
    start.  The returned time will be in the specified format.
    """
    dt_start = datetime.datetime.strptime(start_time_string, format_string)
    dt_end = datetime.datetime.strptime(end_time_string, format_string)

    start_time = time.mktime(dt_start.timetuple()) + dt_start.microsecond / 1000000.0
    end_time = time.mktime(dt_end.timetuple()) + dt_end.microsecond / 1000000.0

    random_time = start_time + random_number * (end_time - start_time)

    return datetime.datetime.fromtimestamp(random_time).strftime(format_string)

例:

print TestData.TestData.random_date("2000/01/01 00:00:00.000000", "2049/12/31 23:59:59.999999", '%Y/%m/%d %H:%M:%S.%f', random.random())

输出: 2028/07/08 12:34:49.977963

It’s modified method of @(Tom Alsberg). I modified it to get date with milliseconds.

import random
import time
import datetime

def random_date(start_time_string, end_time_string, format_string, random_number):
    """
    Get a time at a proportion of a range of two formatted times.
    start and end should be strings specifying times formated in the
    given format (strftime-style), giving an interval [start, end].
    prop specifies how a proportion of the interval to be taken after
    start.  The returned time will be in the specified format.
    """
    dt_start = datetime.datetime.strptime(start_time_string, format_string)
    dt_end = datetime.datetime.strptime(end_time_string, format_string)

    start_time = time.mktime(dt_start.timetuple()) + dt_start.microsecond / 1000000.0
    end_time = time.mktime(dt_end.timetuple()) + dt_end.microsecond / 1000000.0

    random_time = start_time + random_number * (end_time - start_time)

    return datetime.datetime.fromtimestamp(random_time).strftime(format_string)

Example:

print TestData.TestData.random_date("2000/01/01 00:00:00.000000", "2049/12/31 23:59:59.999999", '%Y/%m/%d %H:%M:%S.%f', random.random())

Output: 2028/07/08 12:34:49.977963


回答 23

start_timestamp = time.mktime(time.strptime('Jun 1 2010  01:33:00', '%b %d %Y %I:%M:%S'))
end_timestamp = time.mktime(time.strptime('Jun 1 2017  12:33:00', '%b %d %Y %I:%M:%S'))
time.strftime('%b %d %Y %I:%M:%S',time.localtime(randrange(start_timestamp,end_timestamp)))

参考

start_timestamp = time.mktime(time.strptime('Jun 1 2010  01:33:00', '%b %d %Y %I:%M:%S'))
end_timestamp = time.mktime(time.strptime('Jun 1 2017  12:33:00', '%b %d %Y %I:%M:%S'))
time.strftime('%b %d %Y %I:%M:%S',time.localtime(randrange(start_timestamp,end_timestamp)))

refer


回答 24

    # needed to create data for 1000 fictitious employees for testing code 
    # code relating to randomly assigning forenames, surnames, and genders
    # has been removed as not germaine to the question asked above but FYI
    # genders were randomly assigned, forenames/surnames were web scrapped,
    # there is no accounting for leap years, and the data stored in mySQL

    import random 
    from datetime import datetime
    from datetime import timedelta

    for employee in range(1000):
        # assign a random date of birth (employees are aged between sixteen and sixty five)
        dlt = random.randint(365*16, 365*65)
        dob = datetime.today() - timedelta(days=dlt)
        # assign a random date of hire sometime between sixteenth birthday and yesterday
        doh = datetime.today() - timedelta(days=random.randint(1, dlt-365*16))
        print("born {} hired {}".format(dob.strftime("%d-%m-%y"), doh.strftime("%d-%m-%y")))
    # needed to create data for 1000 fictitious employees for testing code 
    # code relating to randomly assigning forenames, surnames, and genders
    # has been removed as not germaine to the question asked above but FYI
    # genders were randomly assigned, forenames/surnames were web scrapped,
    # there is no accounting for leap years, and the data stored in mySQL

    import random 
    from datetime import datetime
    from datetime import timedelta

    for employee in range(1000):
        # assign a random date of birth (employees are aged between sixteen and sixty five)
        dlt = random.randint(365*16, 365*65)
        dob = datetime.today() - timedelta(days=dlt)
        # assign a random date of hire sometime between sixteenth birthday and yesterday
        doh = datetime.today() - timedelta(days=random.randint(1, dlt-365*16))
        print("born {} hired {}".format(dob.strftime("%d-%m-%y"), doh.strftime("%d-%m-%y")))

回答 25

另一种方法两个日期之间创建随机日期使用np.random.randint()pd.Timestamp().valuepd.to_datetime()具有for loop

# Import libraries
import pandas as pd

# Initialize
start = '2020-01-01' # Specify start date
end = '2020-03-10' # Specify end date
n = 10 # Specify number of dates needed

# Get random dates
x = np.random.randint(pd.Timestamp(start).value, pd.Timestamp(end).value,n)
random_dates = [pd.to_datetime((i/10**9)/(60*60)/24, unit='D').strftime('%Y-%m-%d')  for i in x]

print(random_dates)

输出量

['2020-01-06',
 '2020-03-08',
 '2020-01-23',
 '2020-02-03',
 '2020-01-30',
 '2020-01-05',
 '2020-02-16',
 '2020-03-08',
 '2020-02-09',
 '2020-01-04']

Alternative way to create random dates between two dates using np.random.randint(), pd.Timestamp().value and pd.to_datetime() with for loop:

# Import libraries
import pandas as pd

# Initialize
start = '2020-01-01' # Specify start date
end = '2020-03-10' # Specify end date
n = 10 # Specify number of dates needed

# Get random dates
x = np.random.randint(pd.Timestamp(start).value, pd.Timestamp(end).value,n)
random_dates = [pd.to_datetime((i/10**9)/(60*60)/24, unit='D').strftime('%Y-%m-%d')  for i in x]

print(random_dates)

Output

['2020-01-06',
 '2020-03-08',
 '2020-01-23',
 '2020-02-03',
 '2020-01-30',
 '2020-01-05',
 '2020-02-16',
 '2020-03-08',
 '2020-02-09',
 '2020-01-04']

Python速度测试-时差-毫秒

问题:Python速度测试-时差-毫秒

为了快速测试一段代码,在Python中进行两次比较的正确方法是什么?我尝试阅读API文档。我不确定我是否了解timedelta。

到目前为止,我有以下代码:

from datetime import datetime

tstart = datetime.now()
print t1

# code to speed test

tend = datetime.now()
print t2
# what am I missing?
# I'd like to print the time diff here

What is the proper way to compare 2 times in Python in order to speed test a section of code? I tried reading the API docs. I’m not sure I understand the timedelta thing.

So far I have this code:

from datetime import datetime

tstart = datetime.now()
print t1

# code to speed test

tend = datetime.now()
print t2
# what am I missing?
# I'd like to print the time diff here

回答 0

datetime.timedelta 只是两个日期时间之间的差…所以就像一段时间,以天/秒/微秒为单位

>>> import datetime
>>> a = datetime.datetime.now()
>>> b = datetime.datetime.now()
>>> c = b - a

>>> c
datetime.timedelta(0, 4, 316543)
>>> c.days
0
>>> c.seconds
4
>>> c.microseconds
316543

请注意,它c.microseconds仅返回timedelta的微秒部分!出于计时目的,请始终使用c.total_seconds()

您可以使用datetime.timedelta进行各种数学运算,例如:

>>> c / 10
datetime.timedelta(0, 0, 431654)

不过,查看CPU时间而不是墙上时钟时间可能更有用……虽然这取决于操作系统,但在类Unix系统下,请检查“ time”命令。

datetime.timedelta is just the difference between two datetimes … so it’s like a period of time, in days / seconds / microseconds

>>> import datetime
>>> a = datetime.datetime.now()
>>> b = datetime.datetime.now()
>>> c = b - a

>>> c
datetime.timedelta(0, 4, 316543)
>>> c.days
0
>>> c.seconds
4
>>> c.microseconds
316543

Be aware that c.microseconds only returns the microseconds portion of the timedelta! For timing purposes always use c.total_seconds().

You can do all sorts of maths with datetime.timedelta, eg:

>>> c / 10
datetime.timedelta(0, 0, 431654)

It might be more useful to look at CPU time instead of wallclock time though … that’s operating system dependant though … under Unix-like systems, check out the ‘time’ command.


回答 1

从Python 2.7开始,有了timedelta.total_seconds()方法。因此,要获得经过的毫秒数:

>>> import datetime
>>> a = datetime.datetime.now()
>>> b = datetime.datetime.now()
>>> delta = b - a
>>> print delta
0:00:05.077263
>>> int(delta.total_seconds() * 1000) # milliseconds
5077

Since Python 2.7 there’s the timedelta.total_seconds() method. So, to get the elapsed milliseconds:

>>> import datetime
>>> a = datetime.datetime.now()
>>> b = datetime.datetime.now()
>>> delta = b - a
>>> print delta
0:00:05.077263
>>> int(delta.total_seconds() * 1000) # milliseconds
5077

回答 2

您可能要改用timeit模块

You might want to use the timeit module instead.


回答 3

您还可以使用:

import time

start = time.clock()
do_something()
end = time.clock()
print "%.2gs" % (end-start)

或者您可以使用python分析器

You could also use:

import time

start = time.clock()
do_something()
end = time.clock()
print "%.2gs" % (end-start)

Or you could use the python profilers.


回答 4

我知道这很晚了,但实际上我真的很喜欢使用:

import time
start = time.time()

##### your timed code here ... #####

print "Process time: " + (time.time() - start)

time.time()从纪元开始,您可以得到秒数。因为这是标准时间(以秒为单位),所以您可以简单地从结束时间中减去开始时间来获得处理时间(以秒为单位)。time.clock()对基准测试非常有用,但是如果您想知道过程花费了多长时间,我发现它毫无用处。例如,说“我的过程需要10秒”比说“我的过程需要10个处理器时钟单位”要直观得多。

>>> start = time.time(); sum([each**8.3 for each in range(1,100000)]) ; print (time.time() - start)
3.4001404476250935e+45
0.0637760162354
>>> start = time.clock(); sum([each**8.3 for each in range(1,100000)]) ; print (time.clock() - start)
3.4001404476250935e+45
0.05

在上面的第一个示例中,显示的时间time.clock()为0.05,而time.time()为0.06377

>>> start = time.clock(); time.sleep(1) ; print "process time: " + (time.clock() - start)
process time: 0.0
>>> start = time.time(); time.sleep(1) ; print "process time: " + (time.time() - start)
process time: 1.00111794472

在第二个示例中,即使进程睡眠了一秒钟,处理器时间也以某种方式显示为“ 0”。time.time()正确显示多于1秒。

I know this is late, but I actually really like using:

import time
start = time.time()

##### your timed code here ... #####

print "Process time: " + (time.time() - start)

time.time() gives you seconds since the epoch. Because this is a standardized time in seconds, you can simply subtract the start time from the end time to get the process time (in seconds). time.clock() is good for benchmarking, but I have found it kind of useless if you want to know how long your process took. For example, it’s much more intuitive to say “my process takes 10 seconds” than it is to say “my process takes 10 processor clock units”

>>> start = time.time(); sum([each**8.3 for each in range(1,100000)]) ; print (time.time() - start)
3.4001404476250935e+45
0.0637760162354
>>> start = time.clock(); sum([each**8.3 for each in range(1,100000)]) ; print (time.clock() - start)
3.4001404476250935e+45
0.05

In the first example above, you are shown a time of 0.05 for time.clock() vs 0.06377 for time.time()

>>> start = time.clock(); time.sleep(1) ; print "process time: " + (time.clock() - start)
process time: 0.0
>>> start = time.time(); time.sleep(1) ; print "process time: " + (time.time() - start)
process time: 1.00111794472

In the second example, somehow the processor time shows “0” even though the process slept for a second. time.time() correctly shows a little more than 1 second.


回答 5

以下代码应显示时间说明…

from datetime import datetime

tstart = datetime.now()

# code to speed test

tend = datetime.now()
print tend - tstart

The following code should display the time detla…

from datetime import datetime

tstart = datetime.now()

# code to speed test

tend = datetime.now()
print tend - tstart

回答 6

您可以简单地打印出差异:

print tend - tstart

You could simply print the difference:

print tend - tstart

回答 7

我不是Python程序员,但我确实知道如何使用Google,这就是我发现的内容:您使用“-”运算符。要完成您的代码:

from datetime import datetime

tstart = datetime.now()

# code to speed test

tend = datetime.now()
print tend - tstart

此外,看起来您可以使用strftime()函数格式化时间跨度计算以呈现时间,但是这会让您感到高兴。

I am not a Python programmer, but I do know how to use Google and here’s what I found: you use the “-” operator. To complete your code:

from datetime import datetime

tstart = datetime.now()

# code to speed test

tend = datetime.now()
print tend - tstart

Additionally, it looks like you can use the strftime() function to format the timespan calculation in order to render the time however makes you happy.


回答 8

time.time()/ datetime可以快速使用,但并不总是100%精确。出于这个原因,我喜欢使用其中一个std lib 分析器(尤其是hotshot)来找出问题所在。

time.time() / datetime is good for quick use, but is not always 100% precise. For that reason, I like to use one of the std lib profilers (especially hotshot) to find out what’s what.


回答 9

您可能需要研究配置文件模块。您会更好地了解减速的位置,并且大部分工作将完全自动化。

You may want to look into the profile modules. You’ll get a better read out of where your slowdowns are, and much of your work will be full-on automated.


回答 10

这是一个模仿Matlab / Octave tic toc函数的自定义函数。

使用示例:

time_var = time_me(); # get a variable with the current timestamp

... run operation ...

time_me(time_var); # print the time difference (e.g. '5 seconds 821.12314 ms')

功能:

def time_me(*arg):
    if len(arg) != 0: 
        elapsedTime = time.time() - arg[0];
        #print(elapsedTime);
        hours = math.floor(elapsedTime / (60*60))
        elapsedTime = elapsedTime - hours * (60*60);
        minutes = math.floor(elapsedTime / 60)
        elapsedTime = elapsedTime - minutes * (60);
        seconds = math.floor(elapsedTime);
        elapsedTime = elapsedTime - seconds;
        ms = elapsedTime * 1000;
        if(hours != 0):
            print ("%d hours %d minutes %d seconds" % (hours, minutes, seconds)) 
        elif(minutes != 0):
            print ("%d minutes %d seconds" % (minutes, seconds))
        else :
            print ("%d seconds %f ms" % (seconds, ms))
    else:
        #print ('does not exist. here you go.');
        return time.time()

Here is a custom function that mimic’s Matlab’s/Octave’s tic toc functions.

Example of use:

time_var = time_me(); # get a variable with the current timestamp

... run operation ...

time_me(time_var); # print the time difference (e.g. '5 seconds 821.12314 ms')

Function :

def time_me(*arg):
    if len(arg) != 0: 
        elapsedTime = time.time() - arg[0];
        #print(elapsedTime);
        hours = math.floor(elapsedTime / (60*60))
        elapsedTime = elapsedTime - hours * (60*60);
        minutes = math.floor(elapsedTime / 60)
        elapsedTime = elapsedTime - minutes * (60);
        seconds = math.floor(elapsedTime);
        elapsedTime = elapsedTime - seconds;
        ms = elapsedTime * 1000;
        if(hours != 0):
            print ("%d hours %d minutes %d seconds" % (hours, minutes, seconds)) 
        elif(minutes != 0):
            print ("%d minutes %d seconds" % (minutes, seconds))
        else :
            print ("%d seconds %f ms" % (seconds, ms))
    else:
        #print ('does not exist. here you go.');
        return time.time()

回答 11

您可以像这样使用timeit测试名为module.py的脚本。

$ python -mtimeit -s 'import module'

You could use timeit like this to test a script named module.py

$ python -mtimeit -s 'import module'

回答 12

《箭头》:Python的更好日期和时间

import arrow
start_time = arrow.utcnow()
end_time = arrow.utcnow()
(end_time - start_time).total_seconds()  # senconds
(end_time - start_time).total_seconds() * 1000  # milliseconds

Arrow: Better dates & times for Python

import arrow
start_time = arrow.utcnow()
end_time = arrow.utcnow()
(end_time - start_time).total_seconds()  # senconds
(end_time - start_time).total_seconds() * 1000  # milliseconds

Python日期时间与时间模块之间的差异

问题:Python日期时间与时间模块之间的差异

我试图弄清楚datetimetime模块之间的区别,以及每个模块的用途。

我知道datetime提供日期和时间。该time模块的用途是什么?

将理解示例,并且将特别关注与时区有关的差异。

I am trying to figure out the differences between the datetime and time modules, and what each should be used for.

I know that datetime provides both dates and time. What is the use of the time module?

Examples would be appreciated and differences concerning timezones would especially be of interest.


回答 0

time模块主要用于处理unix时间戳;表示为一个浮点数,以距unix纪元的秒数​​为单位。该datetime模块可以支持许多相同的操作,但是提供了更多的面向对象的类型集,并且对时区的支持有限。

the time module is principally for working with unix time stamps; expressed as a floating point number taken to be seconds since the unix epoch. the datetime module can support many of the same operations, but provides a more object oriented set of types, and also has some limited support for time zones.


回答 1

坚决time防止DST歧义。

专门使用系统time模块而不是datetime模块,以防止夏令时(DST)引起歧义

转换为任何时间格式(包括本地时间)都非常容易:

import time
t = time.time()

time.strftime('%Y-%m-%d %H:%M %Z', time.localtime(t))
'2019-05-27 12:03 CEST'

time.strftime('%Y-%m-%d %H:%M %Z', time.gmtime(t))
'2019-05-27 10:03 GMT'

time.time()是一个浮点数,表示自系统纪元以来的时间(以秒为单位)。time.time()非常适合明确的时间戳记。

如果系统另外运行了网络时间协议(NTP)守护程序,那么最终将获得相当可靠的时基。

这是该模块的文档time

Stick to time to prevent DST ambiguity.

Use exclusively the system time module instead of the datetime module to prevent ambiguity issues with daylight savings time (DST).

Conversion to any time format, including local time, is pretty easy:

import time
t = time.time()

time.strftime('%Y-%m-%d %H:%M %Z', time.localtime(t))
'2019-05-27 12:03 CEST'

time.strftime('%Y-%m-%d %H:%M %Z', time.gmtime(t))
'2019-05-27 10:03 GMT'

time.time() is a floating point number representing the time in seconds since the system epoch. time.time() is ideal for unambiguous time stamping.

If the system additionally runs the network time protocol (NTP) dæmon, one ends up with a pretty solid time base.

Here is the documentation of the time module.


回答 2

当您只需要特定记录的时间时,可以使用时间模块-假设您每天有一个单独的表/文件用于交易,那么您只需要时间。但是,时间数据类型通常用于存储2个时间点之间的时间

这也可以使用datetime完成,但是如果我们只处理特定日期的时间,则可以使用time模块。

日期时间用于存储特定数据和记录时间。就像在出租公司里一样。截止日期将是datetime数据类型。

The time module can be used when you just need the time of a particular record – like lets say you have a seperate table/file for the transactions for each day, then you would just need the time. However the time datatype is usually used to store the time difference between 2 points of time.

This can also be done using datetime, but if we are only dealing with time for a particular day, then time module can be used.

Datetime is used to store a particular data and time for a record. Like in a rental agency. The due date would be a datetime datatype.


回答 3

如果您对时区感兴趣,则应考虑使用pytz。

If you are interested in timezones, you should consider the use of pytz.


类型对象“ datetime.datetime”没有属性“ datetime”

问题:类型对象“ datetime.datetime”没有属性“ datetime”

我收到以下错误:

类型对象“ datetime.datetime”没有属性“ datetime”

在下一行:

date = datetime.datetime(int(year), int(month), 1)

有人知道错误的原因吗?

我导入日期时间from datetime import datetime是否有帮助

谢谢

I have gotten the following error:

type object ‘datetime.datetime’ has no attribute ‘datetime’

On the following line:

date = datetime.datetime(int(year), int(month), 1)

Does anybody know the reason for the error?

I imported datetime with from datetime import datetime if that helps

Thanks


回答 0

日期时间是一个允许处理日期,时间和日期时间(所有都是数据类型)的模块。这意味着datetime它既是顶级模块,又是该模块中的一种类型。这很混乱。

您的错误可能是基于模块的混乱命名,而您或您正在使用的模块已经导入了。

>>> import datetime
>>> datetime
<module 'datetime' from '/usr/lib/python2.6/lib-dynload/datetime.so'>
>>> datetime.datetime(2001,5,1)
datetime.datetime(2001, 5, 1, 0, 0)

但是,如果您导入datetime.datetime:

>>> from datetime import datetime
>>> datetime
<type 'datetime.datetime'>
>>> datetime.datetime(2001,5,1) # You shouldn't expect this to work 
                                # as you imported the type, not the module
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: type object 'datetime.datetime' has no attribute 'datetime'
>>> datetime(2001,5,1)
datetime.datetime(2001, 5, 1, 0, 0)

我怀疑您或您正在使用的模块之一已这样导入: from datetime import datetime

Datetime is a module that allows for handling of dates, times and datetimes (all of which are datatypes). This means that datetime is both a top-level module as well as being a type within that module. This is confusing.

Your error is probably based on the confusing naming of the module, and what either you or a module you’re using has already imported.

>>> import datetime
>>> datetime
<module 'datetime' from '/usr/lib/python2.6/lib-dynload/datetime.so'>
>>> datetime.datetime(2001,5,1)
datetime.datetime(2001, 5, 1, 0, 0)

But, if you import datetime.datetime:

>>> from datetime import datetime
>>> datetime
<type 'datetime.datetime'>
>>> datetime.datetime(2001,5,1) # You shouldn't expect this to work 
                                # as you imported the type, not the module
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: type object 'datetime.datetime' has no attribute 'datetime'
>>> datetime(2001,5,1)
datetime.datetime(2001, 5, 1, 0, 0)

I suspect you or one of the modules you’re using has imported like this: from datetime import datetime.


回答 1

对于python 3.3

from datetime import datetime, timedelta
futuredate = datetime.now() + timedelta(days=10)

For python 3.3

from datetime import datetime, timedelta
futuredate = datetime.now() + timedelta(days=10)

回答 2

你应该用

date = datetime(int(year), int(month), 1)

或改变

from datetime import datetime

import datetime

You should use

date = datetime(int(year), int(month), 1)

Or change

from datetime import datetime

to

import datetime

回答 3

您实际上应该将模块导入其自己的别名中

import datetime as dt
my_datetime = dt.datetime(year, month, day)

与其他解决方案相比,以上优点如下:

  • 调用变量my_datetime而不是date减少混乱,因为datedatetime模块中已经有一个(datetime.date)。
  • 模块和类(都称为datetime)不会相互遮挡。

You should really import the module into its own alias.

import datetime as dt
my_datetime = dt.datetime(year, month, day)

The above has the following benefits over the other solutions:

  • Calling the variable my_datetime instead of date reduces confusion since there is already a date in the datetime module (datetime.date).
  • The module and the class (both called datetime) do not shadow each other.

回答 4

如果您使用过:

from datetime import datetime

然后只需将代码编写为:

date = datetime(int(year), int(month), 1)

但是,如果您使用过:

import datetime

那么只有你可以写:

date = datetime.datetime(int(2005), int(5), 1)

If you have used:

from datetime import datetime

Then simply write the code as:

date = datetime(int(year), int(month), 1)

But if you have used:

import datetime

then only you can write:

date = datetime.datetime(int(2005), int(5), 1)

回答 5

我发现这要容易得多

from dateutil import relativedelta
relativedelta.relativedelta(end_time,start_time).seconds

I found this to be a lot easier

from dateutil import relativedelta
relativedelta.relativedelta(end_time,start_time).seconds

回答 6

我遇到了同样的错误,也许您已经通过仅使用导入了模块,import datetime所以将其更改 form datetime import datetime为only import datetime。我改回来后对我有用。

I run into the same error maybe you have already imported the module by using only import datetime so change form datetime import datetime to only import datetime. It worked for me after I changed it back.


回答 7

from datetime import datetime
import time
from calendar import timegm
d = datetime.utcnow()
d = d.strftime("%Y-%m-%dT%H:%M:%S.%fZ")
utc_time = time.strptime(d,"%Y-%m-%dT%H:%M:%S.%fZ")
epoch_time = timegm(utc_time)
from datetime import datetime
import time
from calendar import timegm
d = datetime.utcnow()
d = d.strftime("%Y-%m-%dT%H:%M:%S.%fZ")
utc_time = time.strptime(d,"%Y-%m-%dT%H:%M:%S.%fZ")
epoch_time = timegm(utc_time)

熊猫中的datetime dtypes read_csv

问题:熊猫中的datetime dtypes read_csv

我正在读取具有多个datetime列的csv文件。我需要在读取文件时设置数据类型,但是日期时间似乎是个问题。例如:

headers = ['col1', 'col2', 'col3', 'col4']
dtypes = ['datetime', 'datetime', 'str', 'float']
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

运行时出现错误:

TypeError:不了解数据类型“ datetime”

事后通过pandas.to_datetime()转换列不是一个选项,我不知道哪些列将是datetime对象。该信息可以更改,并且可以从通知我的dtypes列表的任何信息中获取。

另外,我尝试用numpy.genfromtxt加载csv文件,在该函数中设置dtypes,然后转换为pandas.dataframe,但它会使数据乱码。任何帮助是极大的赞赏!

I’m reading in a csv file with multiple datetime columns. I’d need to set the data types upon reading in the file, but datetimes appear to be a problem. For instance:

headers = ['col1', 'col2', 'col3', 'col4']
dtypes = ['datetime', 'datetime', 'str', 'float']
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

When run gives a error:

TypeError: data type “datetime” not understood

Converting columns after the fact, via pandas.to_datetime() isn’t an option I can’t know which columns will be datetime objects. That information can change and comes from whatever informs my dtypes list.

Alternatively, I’ve tried to load the csv file with numpy.genfromtxt, set the dtypes in that function, and then convert to a pandas.dataframe but it garbles the data. Any help is greatly appreciated!


回答 0

为什么它不起作用

没有为read_csv设置datetime dtype,因为csv文件只能包含字符串,整数和浮点数。

将dtype设置为datetime将使熊猫将datetime解释为对象,这意味着您将以字符串结尾。

熊猫解决这个问题的方法

pandas.read_csv()函数具有名为parse_dates

使用此功能,您可以使用默认date_parserdateutil.parser.parser)快速将字符串,浮点数或整数转换为日期时间

headers = ['col1', 'col2', 'col3', 'col4']
dtypes = {'col1': 'str', 'col2': 'str', 'col3': 'str', 'col4': 'float'}
parse_dates = ['col1', 'col2']
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes, parse_dates=parse_dates)

这将导致熊猫读取col1col2作为字符串,它们很可能是字符串(“ 2016-05-05”等),并且在读取字符串之后,每一列的date_parser都会对该字符串起作用,并返回该函数返回的任何内容。

定义自己的日期解析功能:

pandas.read_csv()函数具有名为date_parser

将其设置为lambda函数将使该特定函数可用于日期解析。

GOTCHA警告

您必须为其提供功能,而不是功能的执行,因此这是正确的

date_parser = pd.datetools.to_datetime

这是不正确的

date_parser = pd.datetools.to_datetime()

熊猫0.22更新

pd.datetools.to_datetime 已移至 date_parser = pd.to_datetime

谢谢@stackoverYC

Why it does not work

There is no datetime dtype to be set for read_csv as csv files can only contain strings, integers and floats.

Setting a dtype to datetime will make pandas interpret the datetime as an object, meaning you will end up with a string.

Pandas way of solving this

The pandas.read_csv() function has a keyword argument called parse_dates

Using this you can on the fly convert strings, floats or integers into datetimes using the default date_parser (dateutil.parser.parser)

headers = ['col1', 'col2', 'col3', 'col4']
dtypes = {'col1': 'str', 'col2': 'str', 'col3': 'str', 'col4': 'float'}
parse_dates = ['col1', 'col2']
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes, parse_dates=parse_dates)

This will cause pandas to read col1 and col2 as strings, which they most likely are (“2016-05-05” etc.) and after having read the string, the date_parser for each column will act upon that string and give back whatever that function returns.

Defining your own date parsing function:

The pandas.read_csv() function also has a keyword argument called date_parser

Setting this to a lambda function will make that particular function be used for the parsing of the dates.

GOTCHA WARNING

You have to give it the function, not the execution of the function, thus this is Correct

date_parser = pd.datetools.to_datetime

This is incorrect:

date_parser = pd.datetools.to_datetime()

Pandas 0.22 Update

pd.datetools.to_datetime has been relocated to date_parser = pd.to_datetime

Thanks @stackoverYC


回答 1

有一个parse_dates参数read_csv可让您定义要视为日期或日期时间的列的名称:

date_cols = ['col1', 'col2']
pd.read_csv(file, sep='\t', header=None, names=headers, parse_dates=date_cols)

There is a parse_dates parameter for read_csv which allows you to define the names of the columns you want treated as dates or datetimes:

date_cols = ['col1', 'col2']
pd.read_csv(file, sep='\t', header=None, names=headers, parse_dates=date_cols)

回答 2

您可以尝试传递实际类型而不是字符串。

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime, datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

但是,如果没有任何可修改的数据,将很难诊断出来。

实际上,您可能希望熊猫将日期解析为时间戳记,因此可能是:

pd.read_csv(file, sep='\t', header=None, names=headers, parse_dates=True)

You might try passing actual types instead of strings.

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime, datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

But it’s going to be really hard to diagnose this without any of your data to tinker with.

And really, you probably want pandas to parse the the dates into TimeStamps, so that might be:

pd.read_csv(file, sep='\t', header=None, names=headers, parse_dates=True)

回答 3

我尝试使用dtypes = [datetime,…]选项,但是

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime, datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

我遇到以下错误:

TypeError: data type not understood

我唯一要做的更改是将datetime替换为datetime.datetime

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime.datetime, datetime.datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

I tried using the dtypes=[datetime, …] option, but

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime, datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

I encountered the following error:

TypeError: data type not understood

The only change I had to make is to replace datetime with datetime.datetime

import pandas as pd
from datetime import datetime
headers = ['col1', 'col2', 'col3', 'col4'] 
dtypes = [datetime.datetime, datetime.datetime, str, float] 
pd.read_csv(file, sep='\t', header=None, names=headers, dtype=dtypes)

如何创建等于15分钟前的DateTime?

问题:如何创建等于15分钟前的DateTime?

我需要创建一个DateTime对象,该对象代表当前时间减去15分钟。

I need to create a DateTime object that represents the current time minus 15 minutes.


回答 0

导入datetime,然后导入神奇的timedelta内容:

In [63]: datetime.datetime.now()
Out[63]: datetime.datetime(2010, 12, 27, 14, 39, 19, 700401)

In [64]: datetime.datetime.now() - datetime.timedelta(minutes=15)
Out[64]: datetime.datetime(2010, 12, 27, 14, 24, 21, 684435)

import datetime and then the magic timedelta stuff:

In [63]: datetime.datetime.now()
Out[63]: datetime.datetime(2010, 12, 27, 14, 39, 19, 700401)

In [64]: datetime.datetime.now() - datetime.timedelta(minutes=15)
Out[64]: datetime.datetime(2010, 12, 27, 14, 24, 21, 684435)

回答 1

 datetime.datetime.now() - datetime.timedelta(minutes=15)
 datetime.datetime.now() - datetime.timedelta(minutes=15)

回答 2

这就是要做的事情:

datetime.datetime.now() - datetime.timedelta(minutes = 15)

timedeltas是专门设计用来允许您减去datetimes 或增加s (差)。

This is simply what to do:

datetime.datetime.now() - datetime.timedelta(minutes = 15)

timedeltas are specifically designed to allow you to subtract or add deltas (differences) to datetimes.


回答 3

from datetime import timedelta    
datetime.datetime.now() - datetime.timedelta(0, 900)

Actually 900 is in seconds. Which is equal to 15 minutes. `15*60 = 900`
from datetime import timedelta    
datetime.datetime.now() - datetime.timedelta(0, 900)

Actually 900 is in seconds. Which is equal to 15 minutes. `15*60 = 900`

回答 4

如果您想查看更多示例,那么在几分钟,几年和几小时内,我提供了两种方法:

import datetime
print(datetime.datetime.now())
print(datetime.datetime.now() - datetime.timedelta(minutes = 15))
print(datetime.datetime.now() + datetime.timedelta(minutes = -15))
print(datetime.timedelta(hours = 5))
print(datetime.datetime.now() + datetime.timedelta(days = 3))
print(datetime.datetime.now() + datetime.timedelta(days = -9))
print(datetime.datetime.now() - datetime.timedelta(days = 9))

我得到以下结果:

2016-06-03 16:04:03.706615
2016-06-03 15:49:03.706622
2016-06-03 15:49:03.706642
5:00:00
2016-06-06 16:04:03.706665
2016-05-25 16:04:03.706676
2016-05-25 16:04:03.706687
2016-06-03
16:04:03.706716

I have provide two methods for doing so for minutes as well as for years and hours if you want to see more examples:

import datetime
print(datetime.datetime.now())
print(datetime.datetime.now() - datetime.timedelta(minutes = 15))
print(datetime.datetime.now() + datetime.timedelta(minutes = -15))
print(datetime.timedelta(hours = 5))
print(datetime.datetime.now() + datetime.timedelta(days = 3))
print(datetime.datetime.now() + datetime.timedelta(days = -9))
print(datetime.datetime.now() - datetime.timedelta(days = 9))

I get the following results:

2016-06-03 16:04:03.706615
2016-06-03 15:49:03.706622
2016-06-03 15:49:03.706642
5:00:00
2016-06-06 16:04:03.706665
2016-05-25 16:04:03.706676
2016-05-25 16:04:03.706687
2016-06-03
16:04:03.706716

回答 5

除了timedelta对象 http://docs.python.org/library/datetime.html外,还使用DateTime

datetime.datetime.now()-datetime.timedelta(minutes=15)

Use DateTime in addition to a timedelta object http://docs.python.org/library/datetime.html

datetime.datetime.now()-datetime.timedelta(minutes=15)


回答 6

datetime.datetime.now() - datetime.timedelta(0, 15 * 60)

timedelta是“时间的变化”。以天为第一个参数,以秒为第二个参数。15 * 60秒是15分钟。

datetime.datetime.now() - datetime.timedelta(0, 15 * 60)

timedelta is a “change in time”. It takes days as the first parameter and seconds in the second parameter. 15 * 60 seconds is 15 minutes.


回答 7

如果您使用的是time.time()时间戳记作为输出

只需使用

CONSTANT_SECONDS = 900 # time  in seconds (900 seconds = 15 min)

current_time = int(time.time())
time_before_15_min = current_time - CONSTANT_SECONDS

您可以根据所需时间更改900秒。

If you are using time.time() and wants timestamp as output

Simply use

CONSTANT_SECONDS = 900 # time  in seconds (900 seconds = 15 min)

current_time = int(time.time())
time_before_15_min = current_time - CONSTANT_SECONDS

You can change 900 seconds as per your required time.


回答 8

只有以下Python 3.7中的代码对我有用

from datetime import datetime,timedelta    
print(datetime.now()-timedelta(seconds=900))

only the below code in Python 3.7 worked for me

from datetime import datetime,timedelta    
print(datetime.now()-timedelta(seconds=900))