How to extract first number between comma in each line with python

Question

I have this input

xxxx,123456,sometext123456,123456,anothertext,123,a

and it is repeated again in first of each line (that is sample of a big log file).

Now I want to extract just first number (123456 after the xxxx) of each line. I tried this regex

(?<=,)[^,]+(?=,)

but it's not working for my needs.

Did none of [these](http://stackoverflow.com/search?q=[python]+extract+word+from+string) help? — Andras Deak -- Слава Україні, Dec 04 '16 at 22:30
@alireza71: Then you may simply do `my_string.split(',')[1]` — Moinuddin Quadri, Dec 04 '16 at 22:35
Will the numbers always be directly after the first comma though? — Max, Dec 04 '16 at 22:36
@Moinuddin Quadri i can't use split because it is just a small part of log file. — alireza71, Dec 04 '16 at 22:39
@alireza71 you read the log file by lines, then `split()` will work perfectly. — MattDMo, Dec 04 '16 at 22:41
@MoinuddinQuadri i can't because word merge together in log file and I avoid to do it. — alireza71, Dec 04 '16 at 22:46
read file using `file.readlines()` and `split` it for each line — Moinuddin Quadri, Dec 04 '16 at 22:46
@MoinuddinQuadri i used already file.readlines() , i don't use split because i have many comma in one line,for example i see one line of log in 15 line of a 15 inch screen :D(i mean it's very long!). — alireza71, Dec 04 '16 at 22:51
@alireza71 if the length of each chunk between comma in your string is fixed, you may use *string slicing*. Even if it is not fixed, I will say *split* is better than *regex* — Moinuddin Quadri, Dec 04 '16 at 22:55
@MoinuddinQuadri thanks with a lot of apologize , it;s work for me string.split(',')[1] — alireza71, Dec 05 '16 at 07:11

score 3 · Accepted Answer · answered Dec 04 '16 at 22:41

Try this regex: ^.*?(\d+).*$, in which group 1 matches the first number after start of the line. Don't forget multiline flag so ^ and $ also matches start and end of a line.

matches = re.finditer(r"^.*?(\d+).*$", input, re.MULTILINE)
for i, match in enumerate(matches):
    print("n = " + match.group(1))  # Group 1 matches the number

How to extract first number between comma in each line with python

1 Answers1