Merge list by dictionary key and sum values if key is same

I have a list of dictionary like this:

# sample data
data = [
    [
        {'id': '1', 'value': '10'},
        {'id': '2', 'value': '5'},
        {'id': '3', 'value': '15'},
        {'id': '4', 'value': '20'},
        # ... many
    ],
    [
        {'id': '2', 'value': '5'},
        {'id': '3', 'value': '5'},
        # ... many
    ],
    [
        {'id': '4', 'value': '10'},
        # ... many
    ],
    # ... many
]

Now I want to loop through all data, and add values if the id is same, and merge back to single list.

# sample output
[
    {'id': '1', 'value': '10'}, # there is no id 1 in other array so the value remain same
    {'id': '2', 'value': '10'}, # same id found in another array so add value
    {'id': '3', 'value': '20'}, # same id found in another array so add value
    {'id': '4', 'value': '30'}, # same id found in another array so add value
]

How can I achieve that?

This is what I’ve done so far:

def merge(data):
    master_list = []
    for i in data:
        thislist =  []
        find = [item.get('id') for item in i]
        for j in i:
            j_id = j.get('id')
            if j_id in find:
                # add some logic here..
                thislist.append(j)
            else:
                thislist.append(j)
        # add some logic here..
        master_list.append(thislist)
    return master_list

print(merge(data))

>Solution :

You can use collections.Counter. First, iterate over data and create dictionaries from id–value pairs. Then cast these dictionaries to collections.Counter and add these counters.

Finally, unpack the counter back into a list of dictionaries.

from collections import Counter
count = Counter()
for lst in data:
    for d in lst:
        count += Counter({d['id']:int(d['value'])})
out = [dict(zip(('id','value'), map(str, pair))) for pair in count.items()]

Output:

[{'id': '1', 'value': '10'},
 {'id': '2', 'value': '10'},
 {'id': '3', 'value': '20'},
 {'id': '4', 'value': '30'}]