Python sum dict values based on keys

Question

How to sum values from dict where values are string. I mean how to sum values where multiply key is same in dictionary.

dict

values = [
    {
        "rashod": 0,
        "prihod": 230.0,
        "prod_name": "r",
        "prod_hola": "t"
    },
    {
        "rashod": 0,
        "prihod": 230.0,
        "prod_name": "r",
        "prod_hola": "t"
    },
    {
        "rashod": 0.0,
        "prihod": 0,
        "prod_name": "c",
        "prod_hola": "f"
    },
    {
        "rashod": 0,
        "prihod": 100.0,
        "prod_name": "c",
        "prod_hola": "f"
    },
    {
        "rashod": 0.0,
        "prihod": 0,
        "prod_name": "a",
        "prod_hola": "b"
    },
    {
        "rashod": 0,
        "prihod": 1500.0,
        "prod_name": "a",
        "prod_hola": "b"
    }]

python

dictf = reduce(lambda x, y: dict((k, v + y[k]) for k, v in x.iteritems()), values)
print dictf

But this sum all values in dict, and output is like:

{'rashod': 1930.0, 'prihod': -17020.0, 'prod_name': 'abcfrtabcfrtabcfrt'}

What I want is output like this:

[{'rashod': 1930.0, 'prihod': -17020.0, 'prod_name': 'a','prod_hola':'b},
{'rashod': 1930.0, 'prihod': -17020.0, 'prod_name': 'c','prod_hola':'f},
{'rashod': 1930.0, 'prihod': -17020.0, 'prod_name': 'r','prod_hola':'t},]

Your input/output example are ambigous : should values be regrouped on "prod_name" only, "prod_hola" only or the combination of "prod_name" and "prod_hola" ? — bruno desthuilliers, Sep 17 '15 at 14:18
Oh and yes: a Karoly Horvarth mentions, your example output doesn't match the input - could you provide matching input and output samples please ? — bruno desthuilliers, Sep 17 '15 at 14:33

score 4 · Accepted Answer · answered Sep 17 '15 at 14:40

Specific solution, with no attempt at cleverness:

def regroup(values):
    groups = dict()
    for d in values:
        key = (d["prod_name"], d["prod_hola"])
        if key in groups:
            group = groups[key]
            group["rashod"] += d["rashod"]
            group["prihod"] += d["prihod"]
        else:
            groups[key] = d.copy()
    return list(groups.values())

And a slightly more generic solution:

def generic_regroup(values, keys):
    groups = dict()
    valkeys = [k for k in values[0] if k not in key]
    for d in values:
        key = tuple(d[k] for k in keys)
        if key in groups:
            group = groups[key]
            for k in valkeys:
                group[k] += d[k]
        else:
            groups[key] = d.copy()
    return list(groups.values())

results = generic_regroup(values, ("prod_name", "prod_hola"))

Now someone will certainly chime in with a much more clever solution involving itertools...

Any suggestion for this : https://stackoverflow.com/questions/66974191/get-sum-of-elemets-in-json-store-data-kivy-to-resolve-scroll-height-question — Nikola Lukic, Apr 06 '21 at 21:07

Pynchia · Answer 2 · 2015-09-17T15:26:07.627

This is a simple and specific solution, I am sure there are more general and cleverer ones. :)

from collections import defaultdict

pr = defaultdict(float)
ra = defaultdict(float)
for el in values:
    combi = (el['prod_name'], el['prod_hola'])
    pr[combi] += el['prihod']
    ra[combi] += el['rashod']

results = [dict(rashod=r, prihod=p, \
                prod_name=nh[0], prod_hola=nh[1]) \
           for r,p,nh in zip(ra.values(), pr.values(), pr)]
print results

gives

[{'rashod': 0.0, 'prihod': 100.0, 'prod_name': 'c', 'prod_hola': 'f'},
 {'rashod': 0.0, 'prihod': 1500.0, 'prod_name': 'a', 'prod_hola': 'b'},
 {'rashod': 0.0, 'prihod': 460.0, 'prod_name': 'r', 'prod_hola': 't'}]

Nathaniel · Answer 3 · 2015-09-18T13:29:57.883

Here's a solution that uses a temporary dict with keys based on the input dict's key value pairs where the values are of type str:

def get_key(d):
    return {k: v for k, v in d.items() if isinstance(v, str)}

def sum_dicts(x, y):
    summed = {k: x.get(k, 0) + y[k] for k, v in y.items() if not isinstance(v, str)}
    summed.update(get_key(y))
    return summed

result = {}
for value in values:
    key = json.dumps(get_key(value))
    result[key] = sum_dicts(result.get(key, {}), value)

print result.values()

Or if you want to use reduce():

def dict_sum_reducer(items, new):
    new_items = map(lambda x: sum_dicts(x, new) if get_key(x) == get_key(new) else x, items)
    if new_items == items:
        new_items.append(new)
    return new_items

print reduce(dict_sum_reducer, values, [])

Thank you for answers. It was really helpfull and learn me things. — Marin, Sep 21 '15 at 07:26

Python sum dict values based on keys

dict

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