Regex :How to remove repetition of the same string?

Question

I'm trying to find the year from the date. the dates are in the format

"Nov.-Dec. 2010"
"Aug. 30 2011-Sept. 3 2011"
"21-21 Oct. 1997"

my regular expression is
q = re.compile("\d\d\d\d")
a = q.findall(date)

so obviously in the list it has two items for a string like "Aug. 30 2011-Sept. 3 2011"

["2011","2011"]

i dont want a repetition, how do i do that?

score 1 · Answer 1 · answered Jul 31 '12 at 07:52

1

You could use a backreference in the regex (see the syntax here):

(\d{4}).*\1

Or you could use the current regex and put this logic in the python code:

if a[0] == a[1]:
    ...

answered Jul 31 '12 at 07:52

Lev Levitsky

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Sorry I can't give you more than +1 – Gabber Jul 31 '12 at 08:08
Then please mark his answer as correct by checking the green V near it! – Gabber Jul 31 '12 at 10:04

score 0 · Accepted Answer · edited May 23 '17 at 11:55

0

Use the following function :

def getUnique(date): 
  q = re.compile("\d\d\d\d") 
  output = [] 
  for x in q.findall(date): 
     if x not in output: 
         output.append(x) 
  return output

It's O(n^2) though, with the repeated use of not in for each element of the input list

see How to remove duplicates from Python list and keep order?

edited May 23 '17 at 11:55

Community

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answered Jul 31 '12 at 07:57

MUY Belgium

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Regex :How to remove repetition of the same string?

2 Answers2