Python，从字符串中删除所有非字母字符 [英] Python, remove all non-alphabet chars from string

问题描述

我正在编写一个 Python MapReduce 字数统计程序.问题是数据中散落着许多非字母字符，我发现这篇文章 从 Python 中的字符串中去除除字母数字字符之外的所有内容 这显示了使用正则表达式的不错解决方案，但我不确定如何实现它

I am writing a python MapReduce word count program. Problem is that there are many non-alphabet chars strewn about in the data, I have found this post Stripping everything but alphanumeric chars from a string in Python which shows a nice solution using regex, but I am not sure how to implement it

def mapfn(k, v):
    print v
    import re, string 
    pattern = re.compile('[\W_]+')
    v = pattern.match(v)
    print v
    for w in v.split():
        yield w, 1

恐怕我不确定如何使用库 re 甚至正则表达式.我不确定如何将正则表达式模式正确应用于传入的字符串(书的行)v 以检索没有任何非字母数字字符的新行.

I'm afraid I am not sure how to use the library re or even regex for that matter. I am not sure how to apply the regex pattern to the incoming string (line of a book) v properly to retrieve the new line without any non-alphanumeric chars.

建议?

推荐答案

使用 re.sub

import re

regex = re.compile('[^a-zA-Z]')
#First parameter is the replacement, second parameter is your input string
regex.sub('', 'ab3d*E')
#Out: 'abdE'

或者，如果您只想删除一组特定的字符(因为在您的输入中使用撇号可能没问题...)

Alternatively, if you only want to remove a certain set of characters (as an apostrophe might be okay in your input...)

regex = re.compile('[,\.!?]') #etc.

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