Find and replace a string in List - Python

Question

I have a list

nums = ['Aero', 'Base Core Newton', 'Node']

I want to replace the string Base with Fine i.e Fine Core , i tried the below code, but it dint work

nums = ['Aero', 'Base Core Newton', 'Node']
nums1=[]
for i in nums:
    if 'Base' in i:
        i.replace('Base','Fine')
        nums1.append(i)

print(nums1)

How can i make this work

This works however we need to have else to complete this or else only the Fine Core Newton is appended to the list — Python_newbie
– Python_newbie, Commented May 17, 2018 at 16:30

Ajax1234 · Accepted Answer · 2018-05-17 16:32:56Z

3

You can use re.sub in a list comprehension. That way, it will be simpler to handle multiple occurrences of 'Base Core' in any elements in nums:

import re
nums = ['Aero', 'Base Core Newton', 'Node']
new_nums = [re.sub('^Base(?=\sCore)', 'Fine', i) for i in nums]

Output:

['Aero', 'Fine Core Newton', 'Node']

regex explanation:

^ -> start of line anchor, anything proceeding must be at the start of the string
Base -> matches the "Base" in the string
?= -> positive lookahead, ^Base will not be matched unless the following pattern in parenthesis is found after ^Base
\sCore -> matches a single space, and then an occurrence of "Core"

edited May 17, 2018 at 16:32

answered May 17, 2018 at 16:24

Ajax1234

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1 Comment

Python_newbie Over a year ago

This works, can you please explain a bit more about this

cdlane · Accepted Answer · 2018-05-17 16:43:15Z

0

I don't think you need to drag re into this. If we use the OP's substitution logic with @Ajax1234's loop structure we get:

nums = ['Aero', 'Base Core Newton', 'Node']
new_nums = [i.replace('Base','Fine') for i in nums]

RESULT

['Aero', 'Fine Core Newton', 'Node']

answered May 17, 2018 at 16:43

cdlane

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