Get unique values in List of Lists in python

array = [['a','b'], ['a', 'b','c'], ['a']]
result = {x for l in array for x in l}

You can use itertools's chain to flatten your array and then call set on it:

from itertools import chain

array = [['a','b'], ['a', 'b','c'], ['a']]
print set(chain(*array))

If you are expecting a list object:

print list(set(chain(*array)))

array = [['a','b'], ['a', 'b','c'], ['a']]
unique_values = list(reduce(lambda i, j: set(i) | set(j), array))