Python - Flatten a dict of lists into unique values?

Question

I have a dict of lists in python:

content = {88962: [80, 130], 87484: [64], 53662: [58,80]}

I want to turn it into a list of the unique val

Answer 1

list(reduce(lambda a, b: a.union(set(b)), content.itervalues(), set()))

The lambda turns the two input arguments into sets and unions them.

The reduce will do a left fold over the list that is passed to it -- in this case, the lists that are the values of your dictionaries.

The reduce will turn the result of this, which is a set back into a list.

This can also be spelled:

list(reduce(lambda a, b: a | set(b), content.itervalues(), set()))