在Python中将数字格式化为字符串

问题:在Python中将数字格式化为字符串

我需要找出如何将数字格式化为字符串。我的代码在这里:

return str(hours)+":"+str(minutes)+":"+str(seconds)+" "+ampm

小时和分钟是整数,而秒是浮点数。str()函数会将所有这些数字转换为十分之几(0.1)。因此,而不是我的字符串输出“ 5:30:59.07 pm”,它将显示类似“ 5.0:30.0:59.1 pm”的内容。

最重要的是,我需要为我执行什么库/函数?

I need to find out how to format numbers as strings. My code is here:

return str(hours)+":"+str(minutes)+":"+str(seconds)+" "+ampm

Hours and minutes are integers, and seconds is a float. the str() function will convert all of these numbers to the tenths (0.1) place. So instead of my string outputting “5:30:59.07 pm”, it would display something like “5.0:30.0:59.1 pm”.

Bottom line, what library / function do I need to do this for me?


回答 0

从Python 3.6开始,可以使用格式化的字符串文字f-strings完成Python中的格式化

hours, minutes, seconds = 6, 56, 33
f'{hours:02}:{minutes:02}:{seconds:02} {"pm" if hours > 12 else "am"}'

str.format以2.7开头的函数:

"{:02}:{:02}:{:02} {}".format(hours, minutes, seconds, "pm" if hours > 12 else "am")

或甚至更旧版本的Python 的字符串格式%运算符,但请参阅文档中的注释:

"%02d:%02d:%02d" % (hours, minutes, seconds)

对于您特定的格式化时间,有time.strftime

import time

t = (0, 0, 0, hours, minutes, seconds, 0, 0, 0)
time.strftime('%I:%M:%S %p', t)

Starting with Python 3.6, formatting in Python can be done using formatted string literals or f-strings:

hours, minutes, seconds = 6, 56, 33
f'{hours:02}:{minutes:02}:{seconds:02} {"pm" if hours > 12 else "am"}'

or the str.format function starting with 2.7:

"{:02}:{:02}:{:02} {}".format(hours, minutes, seconds, "pm" if hours > 12 else "am")

or the string formatting % operator for even older versions of Python, but see the note in the docs:

"%02d:%02d:%02d" % (hours, minutes, seconds)

And for your specific case of formatting time, there’s time.strftime:

import time

t = (0, 0, 0, hours, minutes, seconds, 0, 0, 0)
time.strftime('%I:%M:%S %p', t)

回答 1

从Python 2.6开始,有一个替代str.format()方法:方法。以下是使用现有字符串格式运算符(%)的一些示例:

>>> "Name: %s, age: %d" % ('John', 35) 
'Name: John, age: 35' 
>>> i = 45 
>>> 'dec: %d/oct: %#o/hex: %#X' % (i, i, i) 
'dec: 45/oct: 055/hex: 0X2D' 
>>> "MM/DD/YY = %02d/%02d/%02d" % (12, 7, 41) 
'MM/DD/YY = 12/07/41' 
>>> 'Total with tax: $%.2f' % (13.00 * 1.0825) 
'Total with tax: $14.07' 
>>> d = {'web': 'user', 'page': 42} 
>>> 'http://xxx.yyy.zzz/%(web)s/%(page)d.html' % d 
'http://xxx.yyy.zzz/user/42.html' 

以下是等效片段,但使用str.format()

>>> "Name: {0}, age: {1}".format('John', 35) 
'Name: John, age: 35' 
>>> i = 45 
>>> 'dec: {0}/oct: {0:#o}/hex: {0:#X}'.format(i) 
'dec: 45/oct: 0o55/hex: 0X2D' 
>>> "MM/DD/YY = {0:02d}/{1:02d}/{2:02d}".format(12, 7, 41) 
'MM/DD/YY = 12/07/41' 
>>> 'Total with tax: ${0:.2f}'.format(13.00 * 1.0825) 
'Total with tax: $14.07' 
>>> d = {'web': 'user', 'page': 42} 
>>> 'http://xxx.yyy.zzz/{web}/{page}.html'.format(**d) 
'http://xxx.yyy.zzz/user/42.html'

像Python 2.6+一样,所有Python 3版本(到目前为止)都了解如何实现这两个功能。我毫不客气地从我的核心Python入门书不时提供的Intro + Intermediate Python类的幻灯片中剔除了这些东西。:-)

2018年8月更新:当然,现在我们有了在3.6的F-串功能,我们需要的相同的例子,是的另一种选择:

>>> name, age = 'John', 35
>>> f'Name: {name}, age: {age}'
'Name: John, age: 35'

>>> i = 45
>>> f'dec: {i}/oct: {i:#o}/hex: {i:#X}'
'dec: 45/oct: 0o55/hex: 0X2D'

>>> m, d, y = 12, 7, 41
>>> f"MM/DD/YY = {m:02d}/{d:02d}/{y:02d}"
'MM/DD/YY = 12/07/41'

>>> f'Total with tax: ${13.00 * 1.0825:.2f}'
'Total with tax: $14.07'

>>> d = {'web': 'user', 'page': 42}
>>> f"http://xxx.yyy.zzz/{d['web']}/{d['page']}.html"
'http://xxx.yyy.zzz/user/42.html'

Starting in Python 2.6, there is an alternative: the str.format() method. Here are some examples using the existing string format operator (%):

>>> "Name: %s, age: %d" % ('John', 35) 
'Name: John, age: 35' 
>>> i = 45 
>>> 'dec: %d/oct: %#o/hex: %#X' % (i, i, i) 
'dec: 45/oct: 055/hex: 0X2D' 
>>> "MM/DD/YY = %02d/%02d/%02d" % (12, 7, 41) 
'MM/DD/YY = 12/07/41' 
>>> 'Total with tax: $%.2f' % (13.00 * 1.0825) 
'Total with tax: $14.07' 
>>> d = {'web': 'user', 'page': 42} 
>>> 'http://xxx.yyy.zzz/%(web)s/%(page)d.html' % d 
'http://xxx.yyy.zzz/user/42.html' 

Here are the equivalent snippets but using str.format():

>>> "Name: {0}, age: {1}".format('John', 35) 
'Name: John, age: 35' 
>>> i = 45 
>>> 'dec: {0}/oct: {0:#o}/hex: {0:#X}'.format(i) 
'dec: 45/oct: 0o55/hex: 0X2D' 
>>> "MM/DD/YY = {0:02d}/{1:02d}/{2:02d}".format(12, 7, 41) 
'MM/DD/YY = 12/07/41' 
>>> 'Total with tax: ${0:.2f}'.format(13.00 * 1.0825) 
'Total with tax: $14.07' 
>>> d = {'web': 'user', 'page': 42} 
>>> 'http://xxx.yyy.zzz/{web}/{page}.html'.format(**d) 
'http://xxx.yyy.zzz/user/42.html'

Like Python 2.6+, all Python 3 releases (so far) understand how to do both. I shamelessly ripped this stuff straight out of my hardcore Python intro book and the slides for the Intro+Intermediate Python courses I offer from time-to-time. :-)

Aug 2018 UPDATE: Of course, now that we have the f-string feature in 3.6, we need the equivalent examples of that, yes another alternative:

>>> name, age = 'John', 35
>>> f'Name: {name}, age: {age}'
'Name: John, age: 35'

>>> i = 45
>>> f'dec: {i}/oct: {i:#o}/hex: {i:#X}'
'dec: 45/oct: 0o55/hex: 0X2D'

>>> m, d, y = 12, 7, 41
>>> f"MM/DD/YY = {m:02d}/{d:02d}/{y:02d}"
'MM/DD/YY = 12/07/41'

>>> f'Total with tax: ${13.00 * 1.0825:.2f}'
'Total with tax: $14.07'

>>> d = {'web': 'user', 'page': 42}
>>> f"http://xxx.yyy.zzz/{d['web']}/{d['page']}.html"
'http://xxx.yyy.zzz/user/42.html'

回答 2

Python 2.6以上

可以使用该format()功能,因此您可以使用:

return '{:02d}:{:02d}:{:.2f} {}'.format(hours, minutes, seconds, ampm)

有多种使用此功能的方法,因此,有关更多信息,请查看文档。

Python 3.6+

f字符串是Python 3.6中已添加到该语言的一项新功能。众所周知,这有助于格式化字符串:

return f'{hours:02d}:{minutes:02d}:{seconds:.2f} {ampm}'

Python 2.6+

It is possible to use the format() function, so in your case you can use:

return '{:02d}:{:02d}:{:.2f} {}'.format(hours, minutes, seconds, ampm)

There are multiple ways of using this function, so for further information you can check the documentation.

Python 3.6+

f-strings is a new feature that has been added to the language in Python 3.6. This facilitates formatting strings notoriously:

return f'{hours:02d}:{minutes:02d}:{seconds:.2f} {ampm}'

回答 3

您可以使用C样式字符串格式:

"%d:%d:d" % (hours, minutes, seconds)

特别是在这里看到:https : //web.archive.org/web/20120415173443/http : //diveintopython3.ep.io/strings.html

You can use C style string formatting:

"%d:%d:d" % (hours, minutes, seconds)

See here, especially: https://web.archive.org/web/20120415173443/http://diveintopython3.ep.io/strings.html


回答 4

您可以使用以下代码来实现所需的功能

"%d:%d:d" % (hours, minutes, seconds)

You can use following to achieve desired functionality

"%d:%d:d" % (hours, minutes, seconds)

回答 5

您可以使用str.format()使Python识别字符串中的任何对象。

You can use the str.format() to make Python recognize any objects to strings.


回答 6

python中的str()在整数上不会显示任何小数位。

如果您有一个要忽略小数部分的浮点数,则可以使用str(int(floatValue))。

也许以下代码将演示:

>>> str(5)
'5'
>>> int(8.7)
8

str() in python on an integer will not print any decimal places.

If you have a float that you want to ignore the decimal part, then you can use str(int(floatValue)).

Perhaps the following code will demonstrate:

>>> str(5)
'5'
>>> int(8.7)
8

回答 7

如果您有一个包含小数的值,但是该十进制的值可以忽略不计(即:100.0),并尝试将其设为int,则会出现错误。看起来很傻,但是先调用float可以解决此问题。

str(int(float([variable])))

If you have a value that includes a decimal, but the decimal value is negligible (ie: 100.0) and try to int that, you will get an error. It seems silly, but calling float first fixes this.

str(int(float([variable])))