CODEWITHSUNDEEP
pythonlistdictionary
Mateusz Jagiełło
Mateusz Jagiełło

Reputation: 7144

Python - sum values in dictionary

I have got pretty simple list:

example_list = [
    {'points': 400, 'gold': 2480},
    {'points': 100, 'gold': 610},
    {'points': 100, 'gold': 620},
    {'points': 100, 'gold': 620}
]

How can I sum all gold values? I'm looking for nice oneliner.

Now I'm using this code (but it's not the best solution):

total_gold = 0
for item in example_list:
    total_gold += example_list["gold"]

Upvotes: 106

Views: 138098

Answers (5)

ListenSoftware Louise Ai Agent
ListenSoftware Louise Ai Agent

Reputation: 4233

example_list = [
    {'points': 400, 'gold': 2480},
    {'points': 100, 'gold': 610},
    {'points': 100, 'gold': 620},
    {'points': 100, 'gold': 620}
]

result = np.sum([x['gold'] for x in example_list])


print(result)

output

 4330

Upvotes: 0

xmduhan
xmduhan

Reputation: 1025

from collections import Counter
from functools import reduce
from operator import add

sum_dict = reduce(add, (map(Counter, example_list)))
# Counter({'points': 700, 'gold': 4330})
total_gold = sum_dict['gold']

Upvotes: 7

g.d.d.c
g.d.d.c

Reputation: 47968

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

Upvotes: 229

Ben Burns
Ben Burns

Reputation: 15206

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.

Upvotes: 31

mgilson
mgilson

Reputation: 309841

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.

Upvotes: 8

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