Question 109828 in Json Question posted in
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Summing values in json objects in Python

I have two JSON objects. I want to merge them but wherever the keys are the same the field obj_count should be summed. Is there any way around it in python?

Here is an example of it:
This is the 1st JSON object

[
    {"text": " pen and ink and watercolour", "id": "x32505 ", "obj_count": 1855},
    {"text": " watercolour", "id": "x33202 ", "obj_count": 674},
    {"text": "pencil", "id": "AAT16013 ", "obj_count": 297}
]

And here is the second json object

[
    {"text": " pen and ink and watercolour", "id": "x32505 ", "obj_count": 807},
    {"text": " watercolour", "id": "x33202 ", "obj_count": 97},
    {"text": " ink", "id": "AAT15012 ", "obj_count": 297}
]

What I want is something like this:

[
   {"text":" pen and ink and watercolour","id":"x32505 ","obj_count": 2662 #summed},
   {"text":" watercolour","id":"x33202 ","obj_count": 771 #summed},
   {"text":" ink","id":"AAT15012 ","obj_count":297},
   {"text":"pencil","id":"AAT16013 ","obj_count":297}
]
Tags:

2

Answers


  1. 0

    Yes

    Any loading/saving can be done with the json module (not used below though)

    def sum_list_of_dict(source, add):
    for add_elem in add:
        found = False
        for source_elem in source:
            if add_elem["id"] == source_elem["id"]:
                source_elem["obj_count"] += add_elem["obj_count"]
                found = True
                break  # dupes should not be present
        if not found:
            source.append(add_elem)
    return source


data1 = [
    {"text": "pen and ink and watercolour", "id": "x32505", "obj_count": 1855},
    {"text": "watercolour", "id": "x33202", "obj_count": 674},
    {"text": "pencil", "id": "AAT16013", "obj_count": 297},
]

data2 = [
    {"text": "pen and ink and watercolour", "id": "x32505", "obj_count": 807},
    {"text": "watercolour", "id": "x33202", "obj_count": 97},
    {"text": "ink", "id": "AAT15012", "obj_count": 297},
]

data3 = sum_list_of_dict(data1, data2)

# just for pretty printing
from pprint import pprint
pprint(data3)

    output

    [{'id': 'x32505', 'obj_count': 2662, 'text': 'pen and ink and watercolour'},
 {'id': 'x33202', 'obj_count': 771, 'text': 'watercolour'},
 {'id': 'AAT16013', 'obj_count': 297, 'text': 'pencil'},
 {'id': 'AAT15012', 'obj_count': 297, 'text': 'ink'}]
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  2. 0

    Use a dict to store whether you have seen an id or not

    • if you have, sum their obj_count
    • if you haven’t, just save the item
    values_a = [
    {"text": " pen and ink and watercolour", "id": "x32505 ", "obj_count": 1855},
    {"text": " watercolour", "id": "x33202 ", "obj_count": 674},
    {"text": "pencil", "id": "AAT16013 ", "obj_count": 297}
]

values_b = [
    {"text": " pen and ink and watercolour", "id": "x32505 ", "obj_count": 807},
    {"text": " watercolour", "id": "x33202 ", "obj_count": 97},
    {"text": " ink", "id": "AAT15012 ", "obj_count": 297}
]

result = {}
for item in [*values_a, *values_b]:
    if item['id'] in result:
        result[item['id']]['obj_count'] += item['obj_count']
    else:
        result[item['id']] = item

# back to list of items
result = list(result.values())
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