CODEWITHSUNDEEP
pythonreplace
Sihan Wang
Sihan Wang

Reputation: 307

Replace specific words in python

If I have a string "this is", and I want to replace "is" to "was". When I use replace ("is", "was"), I got "thwas was", but what i am expecting is "this was", is there any solution?

Upvotes: 2

Views: 8029

Answers (1)

DaoWen
DaoWen

Reputation: 33029

You need to do something more sophisticated than a regular string replace. I'd suggest using Regular Expressions (the re module), and using the \b escape sequence to match word boundaries:

import re
re.sub(r"\bis\b", "was", "This is the best island!")

Result: 'This was the best island!'

By using the pattern r"\bis\b" instead of just "is", you ensure that you only match "is" when it appears as a stand-alone word (i.e. there are no numbers, letters or underscore characters directly adjacent to it in the original string).

Here's some more examples of what matches and what doesn't:

re.sub(r"\bis\b", "was", "is? is_number? is, isn't 3is is, ,is, is. hyphen-is. &is")

Result: "was? is_number? was, isn't 3is was, ,was, was. hyphen-was. &was"

Upvotes: 7

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