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 values

[58,64,80,130] 

I wrote a manual solution, but it's a manual solution. I know there are more concise and more elegant way to do this with list comprehensions, map/reduce , itertools , etc. anyone have a clue ?

content = {88962: [80, 130], 87484: [64], 53662: [58,80]} result = set({}) for k in content.keys() :     for i in content[k]:         result.add(i) # and list/sort/print just to compare the output r2 = list( result ) r2.sort() print r2 

Answer 1

Double set comprehension:

Python 3:

sorted({x for v in content.values() for x in v}) 

Python 2:

sorted({x for v in content.itervalues() for x in v}) 

Answer 2

In python3.7 you can use a combination of .values, and chain.

from itertools import chain sorted(set(chain(*content.values()))) # [58, 64, 80, 130]  # another option is `itertools.groupby` from itertools import groupby [k for k, g in groupby(sorted(chain(*content.values())))] 

In python2.7

from itertools import chain sorted(set(chain.from_iterable(content.itervalues()))) # [58, 64, 80, 130]  # another option is `itertools.groupby` [k for k, g in groupby(sorted(chain.from_iterable(content.itervalues())))]