How do I operate on the actual object, not a copy, in a python for loop?

Question

let\'s say I have a list

a = [1,2,3]

I\'d like to increment every item of that list in place. I want to do something as syntactically easy

Answer 1

Here ya go:

# Your for loop should be rewritten as follows:
for index in xrange(len(a)):
    a[index] += 1

Incidentally, item IS a reference to the item in a, but of course you can't assign a new value to an integer. For any mutable type, your code would work just fine:

>>> a = [[1], [2], [3], [4]]
>>> for item in a: item += [1]
>>> a
[[1,1], [2,1], [3,1], [4,1]]