Replace particular strings in python

Question

I need to replace all occurrences of "W32 L30" with "W32in L30in" in a large corpus of text. The numbers after W, L also vary.

I thought of using this regex expressions

[W]([-+]?\d*\.\d+|\d+)
[L]([-+]?\d*\.\d+|\d+)

But these would only find the number after each W and L, so it's still laborious and very time consuming to replace every occurrence so I was wondering if there's a way to do this directly in regex.

The numbers can be floats as well?

willeM_ Van Onsem
– willeM_ Van Onsem

2018-01-19 10:05:40 +00:00
Commented Jan 19, 2018 at 10:05 — willeM_ Van Onsem
– willeM_ Van Onsem, Commented Jan 19, 2018 at 10:05
yes, they can be floats as well

Brian
– Brian

2018-01-19 10:06:30 +00:00
Commented Jan 19, 2018 at 10:06 — Brian
– Brian, Commented Jan 19, 2018 at 10:06

willeM_ Van Onsem · Accepted Answer · 2018-01-19 10:18:09Z

2

You can use a capture group and simplify the regex. Next we can then use a backref to do the replacement. Like:

import re

RGX = re.compile(r'([WL]([-+]?\d*\.\d+|\d+))(in)?')
result = RGX.sub(r'\1in', some_string)

The \1 is used to reference the first capture group: the result of the string we capture with [WL]([-+]?\d*\.\d+|\d+). The last part (in)? optionally also matches the word in, such that in case there is already an in, we simply replace it with the same value.

So if some_string is for instance:

>>> some_string
'A W2 in C3.15 where L2.4in and a bit A4'
>>> RGX.sub(r'\1in', some_string)
'A W2in in C3.15 where L2.4in and a bit A4'

edited Jan 19, 2018 at 10:18

answered Jan 19, 2018 at 10:07

willeM_ Van Onsem

482k33 gold badges483 silver badges624 bronze badges

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

3 Comments

Brian Over a year ago

thanks this is great, but what happens if I use some_string="W32in L45"? I would get "W32inin L45in", but instead I would like "W32in L45in"

willeM_ Van Onsem Over a year ago

@Brian: only if it ends with in? What happens if it would be W32out?

Brian Over a year ago

only if it ends with in

Collectives™ on Stack Overflow

Replace particular strings in python

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related