Removing the lists from a list which are duplicated for some items

Question

I\'m trying to remove the lists from a list which have same first and third items but only keeping the first one. Example list and output:

li=[ [2,4,5], [1,3         


        

Answer 1

Use a set for storing the seen elements. That is faster:

seen = set()
res = []
for entry in li:
    cond = (entry[0], entry[2])
    if cond not in seen:
        res.append(entry)
        seen.add(cond)


[[2, 4, 5], [1, 3, 5]]

ADDITION

Also, the time spend on thinking about telling variables names is typically well spend. Often things first though of as throw-away solutions stick around much longer than anticipated.