Python - sum values in dictionary

Question

I have got pretty simple list:

example_list = [
    {\'points\': 400, \'gold\': 2480},
    {\'points\': 100, \'gold\': 610},
    {\'points\': 100, \'gold\':          


        

Answer 1

If you're memory conscious:

sum(item['gold'] for item in example_list)

If you're extremely time conscious:

sum([item['gold'] for item in example_list])

In most cases just use the generator expression, as the performance increase is only noticeable on a very large dataset/very hot code path.

See this answer for an explanation of why you should avoid using map.

See this answer for some real-world timing comparisons of list comprehension vs generator expressions.

Answer 2

If you prefer map, this works too:

 import operator
 total_gold = sum(map(operator.itemgetter('gold'),example_list))

But I think the generator posted by g.d.d.c is significantly better. This answer is really just to point out the existence of operator.itemgetter.

Answer 3

sum(item['gold'] for item in myList)