Issue with modifying string with python

Question

I need help with coming up with a way to modify:

expr = expr.replace(ip,"("+ip+".~"+ip+")")

in

for ip in input:
    expr = expr.replace(ip,"("+ip+".~"+ip+")")

The problem I am facing is that all instances of ip get replaced. So if ip = "a1" then "a11","a12",....all are replaced with the expression "("+ip+".~"+ip+")"instead of just the element "a1". Here, expr is a string and ip is a list of strings.

What will be an efficient way to do this?

Please provide a sample snippet of input and the desired output. — albert
– albert, Commented Nov 25, 2015 at 1:11

ymyzk · Accepted Answer · 2015-11-25 01:27:19Z

1

You need to use word boundaries...

import re

expr = re.sub(r'\b' + ip + r'\b', "("+ip+".~"+ip+")", expr)

edited Nov 25, 2015 at 1:27

ymyzk

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answered Nov 25, 2015 at 1:12

Avinash Raj

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3 Comments

Brian Over a year ago

What if re is unavailable because, say, that's an assignment?

Avinash Raj Over a year ago

re unavailable? how?

kylieCatt Over a year ago

@Brian You should avoid shadowing standard lib modules in your code, however if it's unavoidable you can import re as something_else

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