Compare length of three lists in python [closed]

Question

Is there a nicer way to compare the length of three lists to make sure they are all the same size besides doing comparisons between each set of variables? What if I wanted to check the length is equal on ten lists. How would I go about doing it?

Answer 1

Using all():

length = len(list1)
if all(len(lst) == length for lst in [list2, list3, list4, list5, list6]):
    # all lists are the same length

Or to find out if any of the lists have a different length:

length = len(list1)
if any(len(lst) != length for lst in [list2, list3, list4, list5, list6]):
    # at least one list has a different length

Note that all() and any() will short-circuit, so for example if list2 has a different length it will not perform the comparison for list3 through list6.

If your lists are stored in a list or tuple instead of separate variables:

length = len(lists[0])
if all(len(lst) == length for lst in lists[1:]):
    # all lists are the same length

Answer 2

Assuming your lists are stored in a list (called my_lists), use something like this:

print len(set(map(len, my_lists))) <= 1

This calculates the lengths of all the lists you have in my_lists and puts these lengths into a set. If they are all the same, the set is going to contain one element (or zero you have no lists).