UserWarning about regular expression - safe to ignore?

[jlounds]

Greetings!

I am trying to extract multiple values at once, e.g.

ds = H.xarray('(:RH:2)|(:TMP:2)')

Is it safe to ignore the following message?

herbie/core.py:823: UserWarning: This pattern is interpreted as a regular expression, and has match groups. To actually get the groups, use str.extract.

Thank you!

Jeremy

[williamhobbs]

It seems to work either way, but I think this will get rid of the warning for you:

ds = H.xarray('(?:RH:2)|(?:TMP:2)')

You could also write it as:

ds = H.xarray('(?:TMP|RH):2 m')

(idea from https://stackoverflow.com/a/71374335/27574852)

[blaylockbk]

Correct, the (?:pattern) syntax is a "non-capturing group" meaning we are just trying to match the string.

A non-capturing group in regular expressions is used to group a subpattern without storing the matched text.

[jlounds]

Thank you both.