Getting 'int' object is not iterable

Question

    cat_sums[cat] += value
TypeError: \'int\' object is not iterable

My input is this:

defaultdict(, {\'composed\'         


        

Answer 1

+, when applied to lists, is concatenation. As BrenBarn said, [1, 2] + [3, 4] == [1, 2, 3, 4].

But if you are actually trying to add numbers, as implied by your statement "I'm trying to add a value to another value inside catnums," then append will not do what you want.

If this is the case then the dictionary you show is probably incorrect. It's not a mapping of words to numbers; it's a mapping of words to lists of numbers (namely the list [0]). If you're trying to maintain a count of words, this is not what you want; you want {'composed': 0, 'elated': 0, ...} (note the lack of square brackets). Then the += statement will work as expected.

If you cannot change the dictionary but simply want to change the number in the list, you can say cat_sums[cat][0] += value. However, it would make far more sense (if this is what you're after) to simply convert the "lists of zero" into plain old zeroes.