How to sum dict elements

user_309111 0
Viewed 66167

In Python, I have list of dicts: 

dict1 = [{'a':2, 'b':3},{'a':3, 'b':4}]

I want one final dict that will contain the sum of all dicts. I.e the result will be: {'a':5, 'b':7}

N.B: every dict in the list will contain same number of key, value pairs.

sum dictionary python
11 Answers

You can also use the pandas sum function to compute the sum:

import pandas as pd
# create a DataFrame
df = pd.DataFrame(dict1)
# compute the sum and convert to dict.
dict(df.sum())

This results in:

{'a': 5, 'b': 7}

It also works for floating points:

dict2 = [{'a':2, 'b':3.3},{'a':3, 'b':4.5}]
dict(pd.DataFrame(dict2).sum())

Gives the correct results:

{'a': 5.0, 'b': 7.8}
user_3863270

Here is another working solution (python3), quite general as it works for dict, lists, arrays. For non-common elements, the original value will be included in the output dict.

def mergsum(a, b):
    for k in b:
        if k in a:
            b[k] = b[k] + a[k]
    c = {**a, **b}
    return c

dict1 = [{'a':2, 'b':3},{'a':3, 'b':4}]
print(mergsum(dict1[0], dict1[1]))
user_16067040
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