Duplicates in lists

Jeff Pinyan jeffp at crusoe.net
Fri Mar 10 13:38:14 CET 2000


[posted & mailed]

On Mar 10, Quinn Dunkan said:

>>> is there someone who has an efficient function that finds
>>> all duplicates in a list?

>def uniq(a):
>    r = {}
>    for i in a:
>        r[i] = None
>    return r.keys()

Your approach loses the order of the keys.  If this is not acceptable, I
offer:

  def ord_uniq(a):
    r = {}
    ret = []
    for i in a:
      if not r.has_key(i):
        ret.append(i)
        r[i] = 1
    return ret

Or, using OrderedDict.py:

  def ord_uniq(a):
    r = OrderedDict.OrderedDict()
    for i in a: r[i] = 1
    return r.keys()

-- 
MIDN 4/C PINYAN, NROTCURPI, US Naval Reserve             japhy at pobox.com
http://www.pobox.com/~japhy/                  http://pinyaj.stu.rpi.edu/
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