Pattern matching python - return multiple items from input in one go

Question

Input:

A->(B, 1), (C, 2), (AKSDFSDF, 1231231) ...

Expected output:

[('A', 1, 2, 1231231)]

Cannot seem to get it to work. My code:

import re

pattern = r"([a-zA-z]+)->(.*)"
r = re.compile(pattern)

print r.findall("A->(B, 1), (C, 2), (AKSDFSDF, 1231231)")
>>> [('A', '(B, 1), (C, 2), (AKSDFSDF, 1231231)')]

That's close enough, but surely it's possible to extract exactly what I want?

I would have though this could work, but it doesnt:

pattern = r"([a-zA-z]+)->([\([a-zA-Z]+,([0-9]+)\)]*)"

That throws empty output (ie. []), while this:

pattern = r"([a-zA-z]+)->((\([a-zA-Z]+,([0-9]+)\))*)"
>>> [('A', '', '', '')]

Any idea?

Moses Koledoye · Accepted Answer · 2016-10-06 21:56:15Z

2

You can use a positive lookahead assertion to pick words starting with a word boundary \b and followed by - or ):

import re

s = 'A->(B, 1), (C, 2), (AKSDFSDF, 1231231)'
pattern = re.compile(r'\b\w+(?=-|\))')
print pattern.findall(s)
#['A', '1', '2', '1231231']

Try it out: https://repl.it/DqSe/0

edited Oct 6, 2016 at 21:56

answered Oct 6, 2016 at 21:47

Moses Koledoye

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2 Comments

Moses Koledoye Over a year ago

@emihir0 Don't forget to accept if the answer helped :)

emihir0 Over a year ago

yes, sorry about that, you answered so quickly that the system wouldn't let me accept the answer yet and then I went off =). Just out of curiosity, why is the \b needed there? For my example it works even without it.

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