python - What is an efficient data structure to store multiple variable-sized sets of numbers? -

i have multiple sets of numbers, so:

set 1: 1,2,3,5,4,3,2,1

set 2: 1,2,1,1

set 3: 1,1,1,0

set 4: 1,9

the number of sets specified user, , how many numbers each set may contain. then, program randomly populate values.

right now, using 2d array dimensions

[maximum(set-sizes)][maximum(elements_in_set)]

and setting unused cells large negative number indicate not of use. although serves purpose, wondering if there better data structure can use.

you can create list of lists:

>>> numbers = [ ...     [1, 2, 3, 5, 4, 3, 2, 1], ...     [1, 2, 1, 1], ...     [1, 1, 1, 0], ...     [1, 9] ... ]  >>> numbers[3] [1, 9]

note describe not sets, because have no order , can contain every element once.

MOno