Pythonic way to do Ruby-like regular expression replace while evaluating the matched string

Question

I have this simple regexp replacement code with a block in it. When Ruby does the gsub the match is passed to the block and whatever is returned from the block is used as replacement.

string = "/foo/bar.####.tif"
string.gsub(/#+/) { | match | "%0#{match.length}d" } # => "/foo/bar.%04d.tif"

Is there a way to do this in Python while keeping it concise? Is there a ++replace++ variant that supports lambdas or the with statement?

It'd be useful to include an example of the intended output for people not familiar with ruby. — Zach Kelling
– Zach Kelling, Commented May 9, 2011 at 17:53
@zeekay: The expected output is in the comment after the second line. — user395760
– user395760, Commented May 9, 2011 at 17:56

user395760 · Accepted Answer · 2011-05-09 17:56:07Z

8

re.sub accepts a function as replacement. It gets the match object as sole parameter and returns the replacement string.

If you want to keep it a oneliner, a lambda will do work: re.sub(r'#+', lambda m: "%0"+str(len(m.group(0))), string). I'd just use a small three-line def to avoid having all those parens in one place, but that's just my opinion.

answered May 9, 2011 at 17:56

user395760

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

1 Comment

Julik Over a year ago

I went for the nested def this time, thanks alot! the trick here was the group(0) thing since the default str() for SRE_Match is not as useful as Ruby's to_s()

inspectorG4dget · Accepted Answer · 2011-05-09 17:54:42Z

1

I'm not well versed in Ruby, but you might be looking for re.sub

Hope this helps

answered May 9, 2011 at 17:54

inspectorG4dget

115k30 gold badges159 silver badges253 bronze badges

Collectives™ on Stack Overflow

Pythonic way to do Ruby-like regular expression replace while evaluating the matched string

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related