sum list of dictionary values

Question

I have a list of dictionary in this form :

[
{\'signal_8\': 1, \'signal_1\': 7, \'signal_10\': 5, \'signal_5\': 2, \'signal_2\': 5, \'signal_6\': 3, \'signa         


        

Answer 1

With itertools.groupby, you could do something like

merged_list = sorted(p for l in original_list for p in l.items())
groups = groupby(merged_list, key=lambda p: p[0])
result = {signal: sum(pair[1] for pair in pairs) for signal, pairs in groups}

If you can assume that each dictionary contains the exact same keys, the above can be simplified to

{k: sum(d[k] for d in original_list) for k in original_list[0]}

Note also that the data analysis library pandas makes operations such as these trivial:

In [70]: import pandas as pd

In [72]: pd.DataFrame(original_list).sum()
Out[72]:
signal_1     21
signal_10    15
signal_2     15
signal_3     18
signal_4     27
signal_5      6
signal_6      9
signal_7     24
signal_8      3
signal_9     12
dtype: int64