>>> timeit.Timer("[x for x in [1,2,3,None] if x]").timeit()
0.7186648845672607
>>> timeit.Timer("filter(None, [1,2,3,None])").timeit()
0.5820250511169434
>>> timeit.Timer('[int(x) for x in ["1","2","3","4","5"]]').timeit()
3.578153133392334
>>> timeit.Timer('map(int,["1","2","3","4","5"])').timeit()
4.9065070152282715