python re sub using regex

Question

I have a requirement to match and replace the continuous spaces that has from 3-20 spaces to just 3 spaces. However, I want to retain the leading spaces as it is. I tried using the negative lookbehind but it is not working as expected.

>>> import re
>>> a="          command1 command2         abc      def       command3     ghi"
>>> re.sub("(?!^)\s{3,20}", "   ", a)
'    command1 command2   abc   def   command3   ghi'
>>> re.sub("(?<!^)\s{3,20}", "   ", a)
'    command1 command2   abc   def   command3   ghi'

Just to re-iterate my requirement, I want to do below changes,

a="          command1 command2         abc      def       command3     ghi"

to

a="          command1 command2   abc   def   command3   ghi"

my python ver is 2.7. Can anyone please help?

Rabinzel · Accepted Answer · 2022-06-25 22:28:11Z

1

You could start checking whitespaces after the first time there is a word.

Check Regex101.

import re
a="          command1 command2         abc      def       command3     ghi"
pat = r"(?<=\w)(\s{3,20})"
re.sub(pat, "   ", a)

'          command1 command2   abc   def   command3   ghi'

answered Jun 25, 2022 at 22:28

Rabinzel

7,9533 gold badges12 silver badges31 bronze badges

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

Comments

Tim Roberts · Accepted Answer · 2022-06-25 22:26:33Z

0

Count the leading spaces and handle them separately.

import re
a="          command1 command2         abc      def       command3     ghi"
lead = len(a)-len(a.lstrip())
a = a[:lead] + re.sub("\s{3,20}", "   ", a[lead:])
print(a)

answered Jun 25, 2022 at 22:26

Tim Roberts

55.3k4 gold badges28 silver badges41 bronze badges

Collectives™ on Stack Overflow

python re sub using regex

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related