CODEWITHSUNDEEP
pythonlist
tipsywacky
tipsywacky

Reputation: 3464

python: how to replace a string in a list of string with a list of strings?

okay here is the example:

data = ['This', 'is', 'a', 'test', 'of', 'the', 'list']
replaceText = 'test'
replaceData =['new', 'test']

i did data.replace(replaceText, replaceData) but it doesn't work. How to replace a string in a list of string with a list of strings? Any help will be appreciated.

Edit: The exact condition is to replace or split the words that contain "s" so I put a loop in it. So the end result will print data = ['Thi', 'i', 'a', 'te','t', 'of', 'the', 'li','t']

Upvotes: 1

Views: 1155

Answers (3)

Jon Clements
Jon Clements

Reputation: 142146

yah, the actually condition needs me to replace or split any string that contains the character 's', say 'test' will be replaced by 'te' and 't' to the list

from itertools import chain
data = ['This', 'is', 'a', 'test', 'of', 'the', 'list']
>>> filter(None, chain.from_iterable(el.split('s') for el in data))
['Thi', 'i', 'a', 'te', 't', 'of', 'the', 'li', 't']

Upvotes: 1

Martijn Pieters
Martijn Pieters

Reputation: 1121884

In a list, find the position of text with .index(), then replace by using slice assignment:

pos = data.index(replaceText)
data[pos:pos+1] = replaceData

This will replace only one occurrence of replaceText at a time. Demo: 

>>> data = ['This', 'is', 'a', 'test', 'of', 'the', 'list']
>>> replaceText = 'test'
>>> replaceData =['new', 'test']
>>> pos = data.index(replaceText)
>>> data[pos:pos+1] = replaceData

To replace all occurences, use pos plus the length of replaceData to skip searching past the previous match:

pos = 0
while True:
    try:
        pos = data.index(replaceText, pos)
    except ValueError:
        break
    data[pos:pos+1] = replaceData
    pos += len(replaceData)

If you need to loop over data while modifying it, use a copy instead:

for n in data[:]:
    # maniplate data

Upvotes: 3

Adam Zalcman
Adam Zalcman

Reputation: 27233

You can use list's index() method to find the position p of replaceText:

p = data.index(replaceText)

and then use the construct

data[start:end] = another_list

to replace elements from p to p+1 (end is not inclusive) with replaceData:

data[p:p+1] = replaceData

Note that index() throws ValueError if replaceText does not exist in data:

try:
  p = data.index(replaceText)
  data[p:p+1] = replaceData
except ValueError:
  # replaceText is not present in data, handle appropriately.

Upvotes: 2

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