Use existing libraries to perform that task, like
import itertools def unique_in_order(iterable): return [k for k,_ in itertools.groupby(iterable)] print(unique_in_order('AAAABBBCCDAABBB')) # ['A', 'B', 'C', 'D', 'A', 'B'] print(unique_in_order(['A'])) # ['A']
With the default group key,
groupby groups identical consecutive elements, yielding tuples with the value and the group of values (that we ignore here, we just need the key)
CLICK HERE to find out more related problems solutions.