1. set 사용
str_test = 'dddaayyyaannn'
print(set(str_test))
#{'a', 'd', 'n', 'y'}
2. join 사용(순서X)
str_unq = ''.join(set(str_test))
print(str_unq)
#anyd
3. OrderedDict 사용(순서O)
from collections import OrderedDict
str_odr =''.join(OrderedDict.fromkeys(str_test))
print(str_odf)
#dayn