Replace specific instance in string - Python

Question

I know that the following is how to replace a string with another string i

line.replace(x, y)

But I only want to replace the second instance of x in the line. How do you do that? Thanks

EDIT I thought I would be able to ask this question without going into specifics but unfortunately none of the answers worked in my situation. I'm writing into a text file and I'm using the following piece of code to change the file.

with fileinput.FileInput("Player Stats.txt", inplace=True, backup='.bak') as file:
    for line in file:
        print(line.replace(chosenTeam, teamName), end='')

But if chosenTeam occurs multiple times then all of them are replaced. How can I replace only the nth instance in this situation.

Possible duplicate of How to replace all occurrences of a string in JavaScript? — Antimony
– Antimony, Commented Sep 22, 2017 at 17:42
Possible duplicate of Replace nth occurrence of substring in string — adder
– adder, Commented Sep 22, 2017 at 17:49

wim · Accepted Answer · 2017-09-22 17:42:11Z

4

That's actually a little tricky. First use str.find to get an index beyond the first occurrence. Then slice and apply the replace (with count 1, so as to replace only one occurrence).

>>> x = 'na'
>>> y = 'banana'
>>> pos = y.find(x) + 1
>>> y[:pos] + y[pos:].replace(x, 'other', 1)
'banaother'

answered Sep 22, 2017 at 17:42

wim

368k114 gold badges682 silver badges819 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

oreofeolurin · Accepted Answer · 2017-09-22 17:47:44Z

2

Bonus, this is a method to replace "NTH" occurrence in a string

def nth_replace(str,search,repl,index):
    split = str.split(search,index+1)
    if len(split)<=index+1:
        return str
    return search.join(split[:-1])+repl+split[-1]

example:

nth_replace("Played a piano a a house", "a", "in", 1) # gives "Played a piano in a house"

answered Sep 22, 2017 at 17:47

oreofeolurin

6463 silver badges16 bronze badges

Comments

Ajax1234 · Accepted Answer · 2017-09-22 17:49:36Z

1

You can try this:

import itertools
line = "hello, hi hello how are you hello"
x = "hello"
y = "something"
new_data = line.split(x)
new_data = ''.join(itertools.chain.from_iterable([(x, a) if i != 2 else (y, a) for i, a in enumerate(new_data)]))

answered Sep 22, 2017 at 17:49

Ajax1234

71.7k9 gold badges67 silver badges110 bronze badges

Collectives™ on Stack Overflow

Replace specific instance in string - Python

3 Answers 3

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related