如何使用Python删除非ASCII字符但保留句点和空格?-Python 实用宝典

如何使用Python删除非ASCII字符但保留句点和空格?

我正在使用.txt文件。我希望文件中的文本字符串不包含非ASCII字符。但是,我想留空格和句点。目前,我也正在剥离它们。这是代码: def onlyascii(char): if ord(char) < 48 or ord(char) > 127: return '' else: return char def get_my_string(file_path): f=open(file_path,'r') data=f.read() f.close() filtered_data=filter(onlyascii, data) filtered_data = filtered_data.lower() return filtered_data 我应该如何修改onlyascii()以保留空格和句点?我想这并不太复杂,但我无法弄清楚。

问题:如何使用Python删除非ASCII字符但保留句点和空格?

我正在使用.txt文件。我希望文件中的文本字符串不包含非ASCII字符。但是,我想留空格和句点。目前,我也正在剥离它们。这是代码:

def onlyascii(char):
    if ord(char) < 48 or ord(char) > 127: return ''
    else: return char

def get_my_string(file_path):
    f=open(file_path,'r')
    data=f.read()
    f.close()
    filtered_data=filter(onlyascii, data)
    filtered_data = filtered_data.lower()
    return filtered_data

我应该如何修改onlyascii()以保留空格和句点?我想这并不太复杂,但我无法弄清楚。

I'm working with a .txt file. I want a string of the text from the file with no non-ASCII characters. However, I want to leave spaces and periods. At present, I'm stripping those too. Here's the code:

def onlyascii(char):
    if ord(char) < 48 or ord(char) > 127: return ''
    else: return char

def get_my_string(file_path):
    f=open(file_path,'r')
    data=f.read()
    f.close()
    filtered_data=filter(onlyascii, data)
    filtered_data = filtered_data.lower()
    return filtered_data

How should I modify onlyascii() to leave spaces and periods? I imagine it's not too complicated but I can't figure it out.


回答 0

您可以使用string.printable过滤字符串中所有不可打印的字符,如下所示:

>>> s = "some\x00string. with\x15 funny characters"
>>> import string
>>> printable = set(string.printable)
>>> filter(lambda x: x in printable, s)
'somestring. with funny characters'

我机器上的string.printable包含:

0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c

编辑:在Python 3上,筛选器将返回可迭代。返回字符串的正确方法是:

''.join(filter(lambda x: x in printable, s))

You can filter all characters from the string that are not printable using string.printable, like this:

>>> s = "some\x00string. with\x15 funny characters"
>>> import string
>>> printable = set(string.printable)
>>> filter(lambda x: x in printable, s)
'somestring. with funny characters'

string.printable on my machine contains:

0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ
!"#$%&\'()*+,-./:;<=>?@[\\]^_`{|}~ \t\n\r\x0b\x0c

EDIT: On Python 3, filter will return an iterable. The correct way to obtain a string back would be:

''.join(filter(lambda x: x in printable, s))

回答 1

更改为其他编解码器的简单方法是使用encode()或decode()。在您的情况下,您想转换为ASCII并忽略所有不支持的符号。例如,瑞典字母å不是ASCII字符:

    >>>s = u'Good bye in Swedish is Hej d\xe5'
    >>>s = s.encode('ascii',errors='ignore')
    >>>print s
    Good bye in Swedish is Hej d

编辑:

Python3:str->字节-> str

>>>"Hej då".encode("ascii", errors="ignore").decode()
'hej d'

Python2:unicode-> str-> unicode

>>> u"hej då".encode("ascii", errors="ignore").decode()
u'hej d'

Python2:str-> unicode-> str(以相反的顺序解码和编码)

>>> "hej d\xe5".decode("ascii", errors="ignore").encode()
'hej d'

An easy way to change to a different codec, is by using encode() or decode(). In your case, you want to convert to ASCII and ignore all symbols that are not supported. For example, the Swedish letter å is not an ASCII character:

    >>>s = u'Good bye in Swedish is Hej d\xe5'
    >>>s = s.encode('ascii',errors='ignore')
    >>>print s
    Good bye in Swedish is Hej d

Edit:

Python3: str -> bytes -> str

>>>"Hej då".encode("ascii", errors="ignore").decode()
'hej d'

Python2: unicode -> str -> unicode

>>> u"hej då".encode("ascii", errors="ignore").decode()
u'hej d'

Python2: str -> unicode -> str (decode and encode in reverse order)

>>> "hej d\xe5".decode("ascii", errors="ignore").encode()
'hej d'

回答 2

根据@artfulrobot,这应该比filter和lambda更快:

re.sub(r'[^\x00-\x7f]',r'', your-non-ascii-string) 

在此处查看更多示例 http://stackoverflow.com/questions/20078816/replace-non-ascii-characters-with-a-single-space/20079244#20079244

According to @artfulrobot, this should be faster than filter and lambda:

re.sub(r'[^\x00-\x7f]',r'', your-non-ascii-string) 

See more examples here Replace non-ASCII characters with a single space


回答 3

您的问题不明确;前两个句子加在一起表示您认为空格和“句点”是非ASCII字符。这是不正确的。等于ord(char)<= 127的所有字符都是ASCII字符。例如,您的函数不包括这些字符!“#$%&\'()* +,-。/,但包括其他几个字符,例如[] {}。

请退后一步,三思而后行,然后编辑您的问题以告诉我们您要做什么,而无需提及ASCII单词,以及为什么您认为ord(char)> = 128这样的chars是可忽略的。另外:哪个版本的Python?输入数据的编码是什么?

请注意,您的代码将整个输入文件读取为单个字符串,并且您对另一个答案的注释(“最佳解决方案”)意味着您无需关心数据中的换行符。如果您的文件包含这样的两行:

this is line 1
this is line 2

结果将是'this is line 1this is line 2'……您真正想要的是什么?

更好的解决方案包括:

  1. 过滤器功能比一个更好的名字 onlyascii
  2. 认识到如果要保留参数,则过滤器功能仅需要返回真实值:

    def filter_func(char):
        return char == '\n' or 32 <= ord(char) <= 126
    # and later:
    filtered_data = filter(filter_func, data).lower()

Your question is ambiguous; the first two sentences taken together imply that you believe that space and "period" are non-ASCII characters. This is incorrect. All chars such that ord(char) <= 127 are ASCII characters. For example, your function excludes these characters !"#$%&\'()*+,-./ but includes several others e.g. []{}.

Please step back, think a bit, and edit your question to tell us what you are trying to do, without mentioning the word ASCII, and why you think that chars such that ord(char) >= 128 are ignorable. Also: which version of Python? What is the encoding of your input data?

Please note that your code reads the whole input file as a single string, and your comment ("great solution") to another answer implies that you don't care about newlines in your data. If your file contains two lines like this:

this is line 1
this is line 2

the result would be 'this is line 1this is line 2' ... is that what you really want?

A greater solution would include:

  1. a better name for the filter function than onlyascii
  2. recognition that a filter function merely needs to return a truthy value if the argument is to be retained:

    def filter_func(char):
        return char == '\n' or 32 <= ord(char) <= 126
    # and later:
    filtered_data = filter(filter_func, data).lower()
    

回答 4

您可以使用以下代码删除非英语字母:

import re
str = "123456790 ABC#%? .(朱惠英)"
result = re.sub(r'[^\x00-\x7f]',r'', str)
print(result)

这将返回

123456790 ABC#%?。()

You may use the following code to remove non-English letters:

import re
str = "123456790 ABC#%? .(朱惠英)"
result = re.sub(r'[^\x00-\x7f]',r'', str)
print(result)

This will return

123456790 ABC#%? .()


回答 5

如果您需要可打印的ASCII字符,则可能应将代码更正为:

if ord(char) < 32 or ord(char) > 126: return ''

等同于string.printable(@jterrace的答案),除了没有返回和制表符('\ t','\ n','\ x0b','\ x0c'和'\ r'),但不对应您问题的范围

If you want printable ascii characters you probably should correct your code to:

if ord(char) < 32 or ord(char) > 126: return ''

this is equivalent, to string.printable (answer from @jterrace), except for the absence of returns and tabs ('\t','\n','\x0b','\x0c' and '\r') but doesnt correspond to the range on your question


回答 6

我强烈推荐使用Fluent Python(Ramalho)。列出受第二章启发的单线Class理解:

onlyascii = ''.join([s for s in data if ord(s) < 127])
onlymatch = ''.join([s for s in data if s in
              'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'])

Working my way through Fluent Python (Ramalho) - highly recommended. List comprehension one-ish-liners inspired by Chapter 2:

onlyascii = ''.join([s for s in data if ord(s) < 127])
onlymatch = ''.join([s for s in data if s in
              'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'])

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