Removing duplicate characters from a string
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.
If order does matter, how about:
>>> foo = 'mppmt'
>>> ''.join(sorted(set(foo), key=foo.index))
'mpt'
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'