Comparing two lists and number of occurrences

Question

What is the best way to compare two lists in Python and to check occurrences?

Consider that

list1 = [a, b, c]
list2 = [a, b, c, d, e, f, g]

I need two things:

to check if list1 contains elements from list2 and get back True or False
to check how many items (len?) from list2 are in list1 and get back integer of those occurrences

score 2 · Accepted Answer · answered May 19 '14 at 08:05

2

You want to use sets here:

intersection = set(list1).intersection(list2)

intersection is now a set of all elements from list1 that also occur in list2. It's length is the number of occurrences.

answered May 19 '14 at 08:05

Martijn Pieters

1 Answers1