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Can anyone help me a bit with regexs? I currently have this: re.split(" +", line.rstrip()), which separates by spaces.
How could I expand this to cover punctuation, too?
4 Answers
The official Python documentation has a good example for this one. It will split on all non-alphanumeric characters (whitespace and punctuation). Literally \W is the character class for all Non-Word characters. Note: the underscore "_" is considered a "word" character and will not be part of the split here.
re.split('\W+', 'Words, words, words.')
See for more examples, search page for "re.split"
Using string.punctuation and character class:
>>> from string import punctuation
>>> r = re.compile(r'[\s{}]+'.format(re.escape(punctuation)))
>>> r.split('dss!dfs^ #$% jjj^')
['dss', 'dfs', 'jjj', '']
import re
st='one two,three; four-five, six'
print re.split(r'\s+|[,;.-]\s*', st)
# ['one', 'two', 'three', 'four', 'five', 'six']
When you consider using a regex to split with any punctuation, you should bear in mind that the \W pattern does not match an underscore (which is a punctuation char, too).
Thus, you can use
import re
tokens = re.split(r'[\W_]+', text)
where [\W_] matches any Unicode non-alphanumeric chars.
Since re.split might return empty items when the match appears at the start or end of string, it is better to use a positive logic and use
import re
tokens = re.findall(r'[^\W_]+', text)
where [^\W_] matches any Unicode alphanumeric chars.
See the Python demo:
import re
text = "!Hello, world!"
print( re.split(r'[\W_]+', text) )
# => ['', 'Hello', 'world', '']
print( re.findall(r'[^\W_]+', text) )
# => ['Hello', 'world']
