In python, given a list of lists, how do you identify the index of a matching element? - 


>>> birds = ['duck', 'chicken', 'goose'] >>> cats = ['tiger', 'lion'] >>> humans = ['human'] >>> at_the_zoo = [birds, cats, humans]

given list of lists at_the_zoo, how locate list tiger in?

for animal in sum(at_the_zoo, []):     if "tiger" == animal:         print "1 help!"

for example, can find tiger in list of animals, , if use enumerate, tell me @ index 3. how figure out part of element 1 of list at_the_zoo. searching duck tell me element 0, etc.

thanks!

i think like:

def find_element(nested_lst, what):     idx, sublst in enumerate(nested_lst):         try:             idx2 = sublst.index(what)             return (idx, idx2)         except valueerror:             pass

should work.

example:

>>> def find_element(nested_lst, what): ...     idx, sublst in enumerate(nested_lst): ...         try: ...             idx2 = sublst.index(what) ...             return (idx, idx2) ...         except valueerror: ...             pass ...  >>> birds = ['duck', 'chicken', 'goose'] >>> cats = ['tiger', 'lion'] >>> humans = ['human'] >>> find_element([birds, cats, humans], 'human') (2, 0) >>> find_element([birds, cats, humans], 'gator')  # returns none if not found. >>> find_element([birds, cats, humans], 'tiger') (1, 0)

it's worth noting on average, list.index o(n) operation means lists aren't efficient data structure testing membership. if actual data supports it, might worthwhile consider using set instead.


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