sum values base duplicate values in dict - python [duplicate]

Question

I have a dict as below:

dict_data = {
  "NAME": ['A', 'B', 'A', 'B', 'C', 'C'],
  "VALUE": [100, 200 , 100 , 200, 300, 300]
}

How to sum values from above dict if NAME duplicate output:

NAME: A
VALUE: 200
NAME: B
VALUE: 400
NAME: C
VALUE: 600

or output to with list:

[A, B, C]
[200, 400, 600]

i using as below:

data = dict.fromkeys(dict_data['NAME'], 0) #create a new dict from value "NAME" of DICT_DATA
for NAME, VALUE in zip(dict_data['NAME'], dict_data['VALUE']):
  data[NAME] += value # Dict NAME A + Dict Name A,... similar to B and C
for key,value in data.items():
 print(list(key))
 print(list(value))

hi @azro, i have tried and it's not worked, but i have using dict.fromkeys as above and it worked — Đặng Lực
– Đặng Lực, Commented Jul 19, 2022 at 7:16

cards · Accepted Answer · 2022-07-13 16:31:20Z

2

Without extra imports.

Use class method fromkeys to set default values

d = dict.fromkeys(dict_data['NAME'], 0)
for k, v in zip(dict_data['NAME'], dict_data['VALUE']):
    d[k] += v

print(d)

or, more verbosely, with the instance method setdefault

d = {}
for k, v in zip(dict_data['NAME'], dict_data['VALUE']):
    d.setdefault(k, 0)
    d[k] += v

These solutions are meant to reply to the comment "If you don't use defualtdict, you can not wtite res[k] += v"

answered Jul 13, 2022 at 16:31

cards

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Comments

azro · Accepted Answer · 2022-07-13 15:10:47Z

2

Use a collections.defaultdict then iterate and sum by grouping on key

dict_data = {"NAME": ["A", "B", "A", "B", "C", "C"], "VALUE": [100, 200, 100, 200, 300, 300]}
from collections import defaultdict

result = defaultdict(int)
for key, value in zip(dict_data['NAME'], dict_data['VALUE']):
    result[key] += value

for key, value in result.items():
    print("NAME", key)
    print("VALUE", value)

keys, values = zip(*result.items())
print(keys)
print(values)

NAME A
VALUE 200
NAME B
VALUE 400
NAME C
VALUE 600

('A', 'B', 'C')
(200, 400, 600)

answered Jul 13, 2022 at 15:10

azro

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Comments

Mahdi F. · Accepted Answer · 2022-07-13 15:13:07Z

2

You can use defaultdict with zero in start.

dict_data = {
  "NAME": ['A', 'B', 'A' , 'B' , 'C' , 'C'],
  "VALUE": [100, 200 , 100 , 200, 300, 300]
}

from collections import defaultdict

# res = defaultdict(lambda : 0)
res = defaultdict(int)

for k,v in zip(dict_data['NAME'], dict_data['VALUE']):
    res[k] += v
    
print(list(res.keys()))
print(list(res.values()))

Output:

['A', 'B', 'C']
[200, 400, 600]

edited Jul 13, 2022 at 15:13

answered Jul 13, 2022 at 15:11

Mahdi F.

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10 Comments

Đặng Lực Over a year ago

Hi I'mahdi, what "lambda : 0" mean ? If value not 100 , 200 , 300 instead 1234, 1234 , 2345 ,2345 ? i think lambda : 0 not correct

Tomerikoo Over a year ago

@ĐặngLực lambda: 0 is just a function that always returns 0. It is used for the first time a key is accessed. It is equivalent to int

Mahdi F. Over a year ago

@ĐặngLực, You can create dict and set what is type of elements like : defaultdict(list) or defaultdict(int) or defaultdict(lambda : 0). If you don't use defualtdict, you can not wtite res[k] += v but when use defaultdict, you can suppose you have key and add value to zero.

Mahdi F. Over a year ago

@ĐặngLực, You can start from 10 instead of zero with : defaultdict(lambda : 10)

Mahdi F. Over a year ago

try this:

dict_data = {   "NAME": ['A', 'B', 'A' , 'B' , 'C' , 'C'],   "VALUE": [100, 200 , 100 , 200, 300, 300],     "NAME2": ['W', 'T', 'W', 'T', 'Y', 'Y'] }  from collections import defaultdict  res = defaultdict(int) res2 = {}  for a,b,c in zip(dict_data['NAME'], dict_data['VALUE'], dict_data['NAME2']):     res[a] += b     res2[a] = c      print(list(res.keys())) print(list(res.values())) print(list(res2.values()))

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