Question

I have a list of lists in this format:

[[<image object1>, source1 , version1],[<image object2>, source2 , version2]...]

I need to compare each list and construct a new list of lists that contains unique source values. When there are duplicated source values, I need to pick the list with the highest version value.

Also, is this the proper data structure I should use?

Answer 1

You can use itertools.groupby and the max function for that:

>>> lst = [['foo', 1, 2], ['asdf', 2, 5], ['bar', 1, 3]]
>>> import itertools as it
>>> from operator import itemgetter
>>> [max(items, key=itemgetter(2)) 
     for _,items in it.groupby(sorted(lst, key=itemgetter(1)), key=itemgetter(1))]
[['bar', 1, 3], ['asdf', 2, 5]]