python regex unexpected match groups

Question

I am trying to find all occurrences of either "_"+digit or "^"+digit, using the regex ((_\^)[1-9])

The groups I'd expect back eg for "X_2ZZZY^5" would be [('_2'), ('^5')] but instead I am getting [('_2', '_'), ('^5', '^')]

Is my regex incorrect? Or is my expectation of what gets returned incorrect?

Many thanks

** my original re used (_|\^) this was incorrect, and should have been (_\^) -- question has been amended accordingly

rdas · Accepted Answer · 2020-07-11 16:44:07Z

2

You have 2 groups in your regex - so you're getting 2 groups. And you need to match atleast 1 number that follows.

try this:

([_\^][1-9]+)

See it in action here

answered Jul 11, 2020 at 16:44

rdas

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Comments

Gustav Rasmussen · Accepted Answer · 2020-07-11 16:43:59Z

2

Demand at least 1 digit (1-9) following the special characters _ or ^, placed inside a single capture group:

import re

text = "X_2ZZZY^5"
pattern = r"([_\^][1-9]{1,})"
regex = re.compile(pattern)
res = re.findall(regex, text)
print(res)

Returning:

['_2', '^5']

answered Jul 11, 2020 at 16:36

Gustav Rasmussen

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