Replace spaces with commas using Regex in python

Question

I want to replace space with comma for this particular pattern only not all spaces: "21311 asd"

Input:

["dog,cat ax 21311 asd","131 MAN"]

Desired output:

["dog,cat ax 21311,asd","131,MAN"]

Code:

input = ["dog,cat ax 21311 asd","131 MAN"]

new_list = []
for i in input:
    word = re.findall(r"\d*\s[a-zA-Z]*" , i)
    new_word = re.sub(word , r"\d*\s[a-zA-Z]*" , i)
    new_list = new_list + new_word
print(new_list)

I know this is wrong syntax, but I don't know how to do it using Regex or any other method.

I'm using Python 3 and Jupyter notebook.

You sure you need RegEx for this? Sounds like something that str.replace can do. Also, you should avoid shadowing built-in names like input. The reference to the input function will be overwritten by your list. — Daniel Fainberg
– Daniel Fainberg, Commented Oct 28, 2022 at 11:37
Actually I didn't ask question properly my bad..I have edited it — Rushabh Nalawade
– Rushabh Nalawade, Commented Oct 28, 2022 at 11:51

AlexanderKondrat · Accepted Answer · 2022-10-28 11:40:04Z

3

Try this:

input = ["dog,cat,21311 asd", "131 MAN"]
print([data.replace(' ', ',') for data in input])

answered Oct 28, 2022 at 11:40

AlexanderKondrat

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1 Comment

Rushabh Nalawade Over a year ago

Actually, I only want to replace a space with comma for particular pattern only like "1554 NAS" or "78412 abcdef" not all spaces.

Daniel Fainberg · Accepted Answer · 2022-10-28 12:00:54Z

1

OK, now that you clarified your request, assuming the pattern you are interested in is

one or more digits followed by a space followed by one or more ASCII letters

Here is the correct way to do it:

import re

pattern = re.compile(r"(\d+)\s([a-zA-Z])")
replacement = r"\1,\2"

inp = ["dog,cat ax 21311 asd", "131 MAN"]

out = [re.sub(pattern, replacement, s) for s in inp]

print(out)

The re.sub function accepts references to matching groups in its repl argument. We group the digits (1) and the letters (2) and thus replace the substring with those two groups with a comma in between.

answered Oct 28, 2022 at 12:00

Daniel Fainberg

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Comments

jvx8ss · Accepted Answer · 2022-10-28 11:41:02Z

1

You are using re.sub() with the wrong argument positions, the correct way is to call it like re.sub(regex, replace, string). Also you are iterating over input incorrectly. That's the right way to do it:

import re
input = ["dog,cat,21311 asd","131 MAN"]

new_list = []
for word in input:
    new_word = re.sub(r" " , ",", word)
    new_list.append(new_word)

print(new_list)

answered Oct 28, 2022 at 11:41

jvx8ss

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2 Comments

Daniel Fainberg Over a year ago

While this is technically correct and an answer to OP question, it does feel a little like cracking a walnut with a sledgehammer. In the same vein, the raw string literal for the space r" " seems a little unnecessary.

Rushabh Nalawade Over a year ago

please help me with this issue.

Алексей Р · Accepted Answer · 2022-10-28 12:04:19Z

1

Solution with re.sub() and pattern with positive Lookahead and Lookbehind

import re
lst = ["dog,cat ax 21311 asd","131 MAN"]

new_list = [re.sub(r"(?<=\d)\s+(?=[a-zA-Z])",",", i) for i in lst]
print(new_list)

['dog,cat ax 21311,asd', '131,MAN']

answered Oct 28, 2022 at 12:04

Алексей Р

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