Python: AttributeError: 'tuple' object has no attribute 'setdefault' -

say list of tuples this:

y=[('a', 'b', 'c'),  ('a', 'c', 'b'),  ('b', 'a', 'c'),  ('b', 'c', 'a'),  ('c', 'a', 'b'),  ('c', 'b', 'a')] 

i trying use reduce() feature make string of each element in y. ''.join(list(x) gives lets 'abc' first iteration.

z=reduce(lambda x, u=dict(): u.setdefault(''.join(list(x)), []).extend(''.join(list(x))), y) 

error:

attributeerror                            traceback (most recent call last) <ipython-input-102-79858e678e78> in <module>() ----> 1 z=reduce(lambda x, u=dict(): u.setdefault(''.join(list(x)), []).extend(''.join(list(x))), y)  <ipython-input-102-79858e678e78> in <lambda>(x, u) ----> 1 z=reduce(lambda x, u=dict(): u.setdefault(''.join(list(x)), []).extend(''.join(list(x))), y)  attributeerror: 'tuple' object has no attribute 'setdefault' 

reduce() called 2 arguments always, u argument set second value in y, tuple. default ignored.

you shouldn't use reduce() here. reduce() need when want use next element in iterator each loop iteration calculate 1 aggregate value.

you mapping instead:

map(''.join, y) 

or use list comprehension:

[''.join(x) x in y]