regular expression re.sub for string formatting in python

Question

Quite new to regular expressions and am trying to get a grasp on them

string = "regex_learning.test"
subbed = re.sub(r'(.*)_learning(.*), r'\1', string)

What I was hoping for is "regex.test" as an ouput when printing subbed, however I just get "regex"

Could someone explain why I am losing the .test?

Thanks in advance

Shailen Tuli · Accepted Answer · 2014-10-16 01:23:41Z

2

Use this:

subbed = re.sub(r'(.*)_learning(.*)', r'\1' + r'\2', string)

You can also write it as:

subbed = re.sub(r'(.*)_learning(.*)', "%s%s" % (r'\1', r'\2'), string)

answered Oct 16, 2014 at 1:23

Shailen Tuli

14.3k6 gold badges42 silver badges52 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

user3234810 Over a year ago

Could you explain what is going on with the + r'\2' there? It helps if I can follow along what the script is saying

Shailen Tuli Over a year ago

\1 gives you the match captured by the first (), and \2 gives you the match captured by the second (). The latter captures the .text part of your string. You want the substituted string to be concatenated from the two matches.

user3234810 Over a year ago

2 mins and counting! Is there a better way to do this than (.*)?

PM 2Ring Over a year ago

@user3234810 : Rather than using *, it's generally better to use *? which gives you non-greedy matching. So (.*) would become (.*?) See *?, +?, ?? in 7.2.1. Regular Expression Syntax.

Collectives™ on Stack Overflow

regular expression re.sub for string formatting in python

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related