Python function that changes every instance of a word in a string to another word

Question

I created this function:

def change(string,word1,word2):
    string=string.split(" ")
    for x in string:
        if x==word1:
            x=word2
    string=" ".join(string)
    print (string)

v1= "X went to buy food. X forgot his car keys in the car."

change(v1,"X","Y")

But the output is still:

"X went to buy food. X forgot his car keys in the car."

The output should be:

"Y went to buy food. Y forgot his car keys in the car."

What is wrong with the code? Why is it not working?

Edit: Guys, Thanks for all solutions, but I wonder Why is this not working? This is so that I don't do similar mistakes in future.

Strings are immutable, and assignment to bare names does not mutate in the first place. Use ``str.replace`` instead. — MisterMiyagi, Jun 14 '20 at 12:59
I think defining `change` like this: `def change(string,word1,word2): print(string.replace(word1, word2))` is somewhat better — Anwarvic, Jun 14 '20 at 13:01
How should the ideal function process this sentence: "X forgot the alphabet ends with 3 chars XYZ"? What I mean is, do you want actual word replacement? Would "XYZ" be preserved as "XYZ"? That would be proper word replacement. — Peaceful James, Jun 14 '20 at 13:02

score -1 · Answer 1 · answered Jun 14 '20 at 13:00

-1

Python has a built-in for this one, .replace():

"The orange orange gleamed of orange.".replace("orange", "purple")
# "The purple purple gleamed of purple."

answered Jun 14 '20 at 13:00

Xiddoc

3,369
3
11
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Stefan Schulz · Answer 2 · 2020-06-14T13:07:49.833

try a simple replacement:

mystring = "X went to buy food. X forgot his car keys in the car."
new_string = mystring.replace("X","Y")

print(mystring)
print(new_string)

output:

X went to buy food. X forgot his car keys in the car.
Y went to buy food. Y forgot his car keys in the car.

or just change your method a little bit:

def change(string,word1,word2):
    string=string.split(" ")
    newstring=[]
    for x in string:
        #print(x)
        if x == word1:
            x=word2
        newstring.append(x)    
    newstring=" ".join(newstring)
    print (newstring)


change(mystring,"X","Y")

output:

Y went to buy food. Y forgot his car keys in the car.

score -2 · Answer 3 · answered Jun 14 '20 at 12:59

-2

Try this:

def change(string,word1,word2):
    return word2.join(string.split(word1))

answered Jun 14 '20 at 12:59

goodvibration

5,980
4
28
61

rajeev dodda · Answer 4 · 2020-06-14T13:07:03.833

-2

def change(string, word1, word2):
    string = string.split(" ")
    for x in range(len(string)):
        if string[x] == word1:
            string[x] = word2
    string = " ".join(string)
    print(string)

Change the for loop as mentioned above will give your expected output.

edited Jun 14 '20 at 13:07

answered Jun 14 '20 at 13:00

rajeev dodda

42
4

1

That won't work. Plus, you're assuming that `word1` and `word2` are single characters. – goodvibration Jun 14 '20 at 13:02
Assuming "string" is list of words. Bcz in the code he used split function on "string" and assigned it to "string" again – rajeev dodda Jun 14 '20 at 13:05
@goodvibration now check the updated code it works. – rajeev dodda Jun 14 '20 at 13:10

score -3 · Answer 5 · answered Jun 14 '20 at 13:03

-3

def change(string,word1,word2):
    changed_string = string.replace(word1,word2)
    print(changed_string)
v1= "X went to buy food. X forgot his car keys in the car."

change(v1,"X","Y")

answered Jun 14 '20 at 13:03

Stalone Balone

46
2
9

10

Mind that the question is "What is wrong with the code? Why is it not working?". – MisterMiyagi Jun 14 '20 at 13:16
4

Please add an explanation. Why was the OP having the problem? How does your code solve this problem? – Run_Script Jun 14 '20 at 19:37
2

While this code may resolve the OP's issue, it's better to include an explanation on how your code addresses the OP's issue. This way, future visitors can learn from your post, & apply it to their own code. SO is not a coding service, but a resource for knowledge. High quality, complete answers reinforce this idea, and are more likely to be upvoted. These features, plus the requirement that all posts be self-contained, are some strengths of SO as a platform that differentiates us from forums. You can edit to add additional info &/or to supplement your explanations with source documentation. – SherylHohman Jun 14 '20 at 23:30
2

Also, if your "Answer" address the question posted by the OP, your response may be considered a non-answer, and could be considered for removal by the community. Please consider 'editing' to meet SO guidelines for Answers, or consider posting aa Comment instead. Visit [guidelines](https://StackOverflow.com/help/how-to-answer) and [help](https://StackOverflow.com/help) for more info. – SherylHohman Jun 14 '20 at 23:38

Python function that changes every instance of a word in a string to another word

5 Answers5