What is the most efficient way to search nested lists in python?

Question

I have a list that contains nested lists and I need to know the most efficient way to search within those nested lists.

e.g., if I have

[[\'a\',\'b\         


        

Answer 1

Use a generator expression, here the whole list will not be traversed as generator generate results one by one:

>>> lis = [['a','b','c'],['d','e','f']]
>>> 'd' in (y for x in lis for y in x)
True
>>> gen = (y for x in lis for y in x)
>>> 'd' in gen
True
>>> list(gen)
['e', 'f']

~$ python -m timeit -s "lis=[['a','b','c'],['d','e','f'],[1,2,3],[4,5,6],[7,8,9],[10,11,12],[13,14,15],[16,17,18]]" "'d' in (y for x in lis for y in x)"
    100000 loops, best of 3: 2.96 usec per loop

~$ python -m timeit -s "lis=[['a','b','c'],['d','e','f'],[1,2,3],[4,5,6],[7,8,9],[10,11,12],[13,14,15],[16,17,18]]" "'d' in [y for x in lis for y in x]"
    100000 loops, best of 3: 7.4 usec per loop