Python lint issue : invalid escape sequence '\/'

Question

This is my python code line which is giving me invalid escape sequence '/' lint issue.

pattern = 'gs:\/\/([a-z0-9-]+)\/(.+)$'  # for regex matching

It is giving me out that error for all the backslash I used here . any idea how to resolve this ?

You should be using a raw string for a regular expression, so the backslashes will be passed through transparently to the regexp engine. — Barmar, May 10 '22 at 20:15
@Barmar so how would the above pattern will look for regex matching? — quicksilver, May 10 '22 at 20:16
@quicksilver, what do you mean by that question? `pattern = 'gs://([a-z0-9-]+)/(.+)$'` is enough on its own; it doesn't need anything else to "look for regex matching". The answer advising use of a raw string is good for the future so you can use backslashes in later versions of your regex, but your current regex doesn't strictly need it; all you need to do is take out the unnecessary backslashes. — Charles Duffy, May 10 '22 at 20:26

score 4 · Accepted Answer · answered May 10 '22 at 20:19

There's two issues here:

Since this is not a raw string, the backslashes are string escapes, not regexp escapes. Since \/ is not a valid string escape sequence, you get that warning. Use a raw string so that the backslashes will be ignored by the string parser and passed to the regexp engine. See What exactly is a "raw string regex" and how can you use it?
In some languages / is part of the regular expression syntax (it's the delimiter around the regexp), so they need to be escaped. But Python doesn't use / this way, so there's no need to escape them in the first place.

Use this:

pattern = r'gs://([a-z0-9-]+)/(.+)$'  # for regex matching

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