Add a value to an element in a list of sets
- by Kapelson
Hello. I'm using python, and I have a list of sets, constructed like this:
list = [set([])]*n
...where n is the number of sets I want in the list. I want to add a value to a specific set in the list. Say, the second set. I tried
list[1].add(value)
But this instead adds the value to each set in the list. This behaviour is pretty non-intuitive to me. Through further tests, I think I've found the problem: the list apparently contains 10 instances of the same set, or ten pointers to the same set, or something. Constructing the list through repeated calls of
list.append(set([]))
allowed me to use the syntax above to add elements to single sets. So my question is this: what exactly is going on in my first list-construction technique? It is clear I don't understand the syntax so well. Also, is there a better way to intialize an n-element list? I've been using this syntax for a while and this is my first problem with it.
