How can I replace each occurrence of a substring independently of the others?

Question

I have a sentence like this:

sentence = "it is a stupid book and a stupid hat and a stupid computer"

and I want to replace the word "stupid" with the word "silly". And create a sentence for each replacement.

The result is something like this:

"it is a silly book and a stupid hat and a stupid computer"
"it is a stupid book and a silly hat and a stupid computer"
"it is a stupid book and a stupid hat and a silly computer"

I mean the creating just 3 sentences each one for each replacement.
I found the method replace() in Python but the count parameter determines the number of replacements not the one that I want. Could anyone help me?

Asked By: HosseinSedghian

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Source

Answer 1

One solution:

string = "it is a stupid book and a stupid hat and a stupid computer"

for i in range(string.count('stupid')):
    new = string.replace('stupid', 'silly', i+1)
    new = new.replace('silly', 'stupid', i)
    print(new)

EDIT

Another solution with a list comprehension:

string = "it is a stupid book and a stupid hat and a stupid computer"

word1 = 'stupid'
word2 = 'silly'

strings = [string.replace(word1, word2, i+1).replace(word2, word1, i) for i in range(string.count(word1))]

print(strings)

EDIT2
If word2 happens to be in string (as W. Ding comment), then you can try this (choosing an unlikely string as long as you want):

string = "silly...it is a stupid book and a stupid hat and a stupid computer"
word1 = 'stupid'
word2 = 'silly'
unlikely = '$*$ù^$*ù*;;;,:;!::*ù*$^^$$^d^^d^eêê'


strings = [string.replace(word1, unlikely, i+1).
                  replace(unlikely, word1, i).
                  replace(unlikely, word2) for i in range(string.count(word1))]

print(strings)

Answered By: zigma12

Answer 2

A robust but not elegant way is to first split the sentence by the word you want to replace. And then concatenate the pieces with different combinations of linking words:

sentence = "it is a stupid book and a stupid hat and a stupid computer"
old = "stupid"
new = "silly"
pieces = sentence.split(old)

new_sentences = []
for pos in range(1, len(pieces)):
    new_sentences.append(old.join(pieces[:pos]) + new + old.join(pieces[pos:]))
print(new_sentences)

Thanks for @user3840170 making it shorter and easier to remember.

Output:

['it is a silly book and a stupid hat and a stupid computer',
 'it is a stupid book and a silly hat and a stupid computer',
 'it is a stupid book and a stupid hat and a silly computer']

Answered By: W. Ding

Answer 3

Regex solution:

import re

sentence = "it is a stupid book and a stupid hat and a stupid computer"

for match in re.finditer(r'bstupidb', sentence):
    print(sentence[:match.start()] + 'silly' + sentence[match.end():])

Try it online!

Answered By: Kelly Bundy

How can I replace each occurrence of a substring independently of the others?

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