What's The Most Pythonic Way To Apply A Function On Every Word In A String With Multiple Types Of White Space Characters?

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 = '

Solution 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'

Solution 2:

Use regular expressions, where you can easily get whole words and also whole chunks of continuous whitespace.