CODEWITHSUNDEEP
pythonregex
Jadon Erwin
Jadon Erwin

Reputation: 661

Regex to find repeating numbers even if they are separated

I'm trying to create a regular expression that will tell me if I have two or more repeating numbers in a string separated by a comma. For example "10,2,3,4,5,6,7,8,9,10" would return true because there are two tens.

I think I am close. So far I have:

if re.match(r"(\d+),.+\1",line):

Thanks!

Upvotes: 0

Views: 100

Answers (1)

Nick
Nick

Reputation: 147216

You don't need regex for this. Just convert into a list using split, then convert that into a set (which will contain only the unique numbers in the list) and compare the lengths:

line = "10,2,3,4,5,6,7,8,9,10"

lst = line.split(',')
unq = set(lst)
if (len(lst) != len(unq)):
    # non-unique numbers present

If you want to use regex, you need to use re.search rather than re.match, as re.match requires matches to begin at the start of the string, which would preclude matching 2 in "1,2,3,4,5,6,2,7,8,9,10". Also, you need to surround your (\d+) with word breaks (\b), so that 1 in "1,2,3,4,5,6,2,7,8,9,10" doesn't then match against the 1 in 10. This regex will give you the results you want:

m = re.search(r'\b(\d+)\b.*\b\1\b', line)
if m:
    print('Duplicate number ' + m.group(1))

Upvotes: 5

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