Fetch key of a value from dictionary with multiple values for single key

Question

Given a dictionary

collision_domain  = {0: [0, 1, 2], 1: [2, 3, 4]}

this code should output domain 0:

search = 1
for dom, node in collision_domain.items():
    if node == search:
        print("domain", dom)

How do we get that?

Does this answer your question? [Fastest way to check if a value exists in a list](https://stackoverflow.com/questions/7571635/fastest-way-to-check-if-a-value-exists-in-a-list) — mkrieger1, Aug 18 '20 at 12:32
I think dictionary keys have to be strings, try changing node==search to node==str(search) — Lebster, Aug 18 '20 at 12:33
@Lebster The main requirement for dict keys is that they must be hashable — Chris_Rands, Aug 18 '20 at 12:36
@Pavitra To clear this up for you, `==` tests whether two objects are *equal* but you want to test whether `1` is *contained* in the list `[0, 1, 2]`. You need to use the `in` operator instead of `==`. — mkrieger1, Aug 18 '20 at 12:38

score 2 · Answer 1 · answered Aug 18 '20 at 12:38

What we need to do here is search inside the list on each iteration of the loop.

Note that the search value comes first and then the list. if search in node:

Final Code:

for dom, node in collision_domain.items():
    if search in node:
        print("domain", dom)

1 Answers1