python regex find text with digits

Question

I have text like:

sometext...one=1290...sometext...two=12985...sometext...three=1233...

How can I find one=1290 and two=12985 but not three or four or five? There are can be from 4 to 5 digits after =. I tried this:

import re
pattern = r"(one|two)+=+(\d{4,5})+\D"
found = re.findall(pattern, sometext, flags=re.IGNORECASE)
print(found)

It gives me results like: [('one', '1290')]. If i use pattern = r"((one|two)+=+(\d{4,5})+\D)" it gives me [('one=1290', 'one', '1290')]. How can I get just one=1290?

DeepSpace · Accepted Answer · 2017-07-04 07:42:51Z

4

You were close. You need to use a single capture group (or none for that matter):

((?:one|two)+=+\d{4,5})+

Full code:

import re

string = 'sometext...one=1290...sometext...two=12985...sometext...three=1233...'

pattern = r"((?:one|two)+=+\d{4,5})+"
found = re.findall(pattern, string, flags=re.IGNORECASE)
print(found)
# ['one=1290', 'two=12985']

answered Jul 4, 2017 at 7:42

DeepSpace

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1 Comment

DatHydroGuy Over a year ago

Exactly this. To summarize what the findall() method returns, remember the following: When called on a regex with no groups, such as \d\d\d-\d\d\d-\d\d\d\d, the method findall() returns a list of string matches, such as ['123-456-7890', '987-654-3210']. When called on a regex that has groups, such as (\d\d\d)-(\d\d\d)-(\d\d\d\d), the method findall() returns a list of tuples of strings (one string for each group), such as [('123', '456', '7890'), ('987', '654', '3210')]. Here, the outermost capture group is returned to give the answer(s) you require.

Thomas Ayoub · Accepted Answer · 2017-07-04 07:42:58Z

1

Make the inner groups non capturing: ((?:one|two)+=+(?:\d{4,5})+\D)

answered Jul 4, 2017 at 7:42

Thomas Ayoub

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Comments

Tom Lord · Accepted Answer · 2017-07-04 07:43:08Z

1

The reason that you are getting results like [('one', '1290')] rather than one=1290 is because you are using capture groups. Use:

r"(?:one|two)=(?:\d{4,5})(?=\D)"

I have removed the additional + repeaters, as they were (I think?) unnecessary. You don't want to match things like oneonetwo===1234, right?
Using (?:...) rather than (...) defines a non-capture group. This prevents the result of the capture from being returned, and you instead get the whole match.
Similarly, using (?=\D) defines a look-ahead - so this is excluded from the match result.

answered Jul 4, 2017 at 7:43

Tom Lord

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