在具有多种类型的空白字符的字符串中的每个单词上应用函数的最有效的方法是什么？

Question

Suppose I have a function

def f(a):
  return a[::-1]

I want to apply the function f to every word on a string. If the string consists only of spaces, I can do

>>> s = '   this  is a banana   '
>>> ' '.join(map(f, s.split(' ')))
'   siht  si a ananab   '

But how can I do this when the string consists of multiple types of white spaces? (eg, \\t and \\n)

For example, I want to change

'\t  \t this  is a\tbanana   \n'

to

'\t  \t siht  si a\tananab   \n'

Answer 1

Use a regular expression, the re.sub() function accepts a function to do the substitutions. Match non-whitespace instead:

re.sub(r'[^\s]+', lambda m: f(m.group(0)), s)

The function is passed a match object ; using .group(0) you can extract the matched text to pass it to your function. The return value is used to replace the original matched text in the output string.

Demo:

>>> import re
>>> def f(a):
...   return a[::-1]
...
>>> s = '\t  \t this  is a\tbanana   \n'
>>> re.sub(r'[^\s]+', lambda m: f(m.group(0)), s)
'\t  \t siht  si a\tananab   \n'

Answer 2

使用正则表达式，您可以在其中轻松获得整个单词以及连续空白的整个块。