How do you write a regex in python which picks out all strings beginning with a specific number

Question

I'm trying to get this regex to pick out both 7gh and 7ui but I can only get it to pick out the first one. If anyone knows how to amend the regex such that it also picks out 7ui, I would seriously appreciate it. I should also point out that I mean strings separated by a space.

b = re.search(r'^7\w+','7gh ghj 7ui')
c = b.group()

Possible duplicate of [Python regex findall](https://stackoverflow.com/questions/7752551/python-regex-findall) — Sayse, Jul 31 '17 at 08:42
What about `a7b`? Both solutions would currently pick it as `7b` - is that correct? — Sebastian Proske, Jul 31 '17 at 08:46

score 2 · Answer 1 · answered Jul 31 '17 at 08:43

2

Remove ^ and use findall() :

>>> re.findall(r'7\w+','7gh ghj 7ui')
['7gh', '7ui']

answered Jul 31 '17 at 08:43

akash karothiya

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that doesn't work. That only captures the first string with 7 – bobsmith76 Jul 31 '17 at 08:52

score 1 · Answer 2 · edited Sep 23 '17 at 18:15

1

You need to remove ^ (start of string anchor) and use re.findall to find all non-overlapping matches of pattern in string:

import re
res = re.findall(r'7\w+','7gh ghj 7ui')
print(res)

See the Python demo

If you need to get these substrings as whole words, enclose the pattern with a word boundary, \b:

res = re.findall(r'\b7\w+\b','7gh ghj 7ui')

edited Sep 23 '17 at 18:15

Graham

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answered Jul 31 '17 at 08:43

Wiktor Stribiżew

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difference of few sec :) – akash karothiya Jul 31 '17 at 08:44
They probably want a word boundary in there to avoid picking up `bob7something`... – Jon Clements Jul 31 '17 at 08:45
@akashkarothiya Yeah, but I think OP might need further tweaking, so, I also suggest a word boundary. – Wiktor Stribiżew Jul 31 '17 at 08:46
@WiktorStribiżew much appreciated :) helpful – akash karothiya Jul 31 '17 at 08:53
@bobsmith76 you should also consider Wikter's 2nd method for future reference, using `\b`, Please see – akash karothiya Jul 31 '17 at 08:56

score 0 · Answer 3 · answered Jul 31 '17 at 08:49

0

You may find it easier to just not use regex

[s for s in my_string.split() if s.startswith('7')]

answered Jul 31 '17 at 08:49

Sayse

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No, I'm trying to understand how regexes work. I'm not trying to get something done. – bobsmith76 Jul 31 '17 at 08:51

How do you write a regex in python which picks out all strings beginning with a specific number

3 Answers3