Removing duplicate characters from a string

Solution 1:

If order does not matter, you can use

"".join(set(foo))

set() will create a set of unique letters in the string, and "".join() will join the letters back to a string in arbitrary order.

If order does matter, you can use a dict instead of a set, which since Python 3.7 preserves the insertion order of the keys. (In the CPython implementation, this is already supported in Python 3.6 as an implementation detail.)

foo = "mppmt"
result = "".join(dict.fromkeys(foo))

resulting in the string "mpt". In earlier versions of Python, you can use collections.OrderedDict, which has been available starting from Python 2.7.

Solution 2:

If order does matter, how about:

>>> foo = 'mppmt'
>>> ''.join(sorted(set(foo), key=foo.index))
'mpt'

Solution 3:

If order is not the matter:

>>> foo='mppmt'
>>> ''.join(set(foo))
'pmt'

To keep the order:

>>> foo='mppmt'
>>> ''.join([j for i,j in enumerate(foo) if j not in foo[:i]])
'mpt'

Solution 4:

Create a list in Python and also a set which doesn't allow any duplicates. Solution1 :

def fix(string):
    s = set()
    list = []
    for ch in string:
        if ch not in s:
            s.add(ch)
            list.append(ch)

    return ''.join(list)        

string = "Protiijaayiiii"
print(fix(string))

Method 2 :

s = "Protijayi"

aa = [ ch  for i, ch in enumerate(s) if ch not in s[:i]]
print(''.join(aa))

Solution 5:

As was mentioned "".join(set(foo)) and collections.OrderedDict will do. A added foo = foo.lower() in case the string has upper and lower case characters and you need to remove ALL duplicates no matter if they're upper or lower characters.

from collections import OrderedDict
foo = "EugeneEhGhsnaWW"
foo = foo.lower()
print "".join(OrderedDict.fromkeys(foo))

prints eugnhsaw