Question

I have a list: v = [1,2,2,3]. I would like to use this list as a key. I can do it “manually”:

x = {}
x[1,2,2,3] = 7

But

x[v] = 7

does not work. What is the easiest way to do what I need to do?

ADDED

I imagine the solution as something like that:

x[open(v)] = 7

Answer 1

The problem is that keys must be immutable, which lists are not. Tuples, however, are.

Simply convert v to a tuple:

x[tuple(v)] = 7

To elaborate, the above is the same as writing

x[1,2,2,3] = 7

and the latter is a syntactic variation of

x[(1,2,2,3)] = 7