如何在列表中添加命令数据

Question

I have a list of dicts which has a lot of values like

"resultset":[
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"10",
    },
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"11",
    },
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"10",
    },
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"14",
    },
    {
       "Car":"Lambo ",
       "Value_in_US":"11",
    },
    {
       "Car":"Porshe Nine",
       "Value_in_US":"12",
    },
    {
       "Car":"Porshe Nine",
       "Value_in_US":"10",
    },
 ]

I am trying to separate the list of unique Cars with corresponding values, The output i am expecting is

{
'Porshe Nine' : [10,12],
'Lambo': [11],
'Aston Martin DB Nine': [10,11,10,14]
}

I was trying something like

test = {}
    for data in  result['resultset']:
        test[data['Car']] = ???

I am not sure how to get the values right as i mentioned

Answer 1

Sounds like a defaultdict would be useful here:

from collections import defaultdict
test = defaultdict(list)
for data in result['resultset']:
    test[data['Car']].append(data['Value_in_US'])

Very similar logic to the code you already have, but what defaultdict lets you do is assume that there's already a key/value pair of car:list of prices. Notice that we don't need to check if the car is already in the dictionary, we just append the price.

Answer 2

Without any additional imports:

test = {}
for data in result['resultset']:
    if not data['Car'] in test.keys():
        test[data['Car']] = []
    
    test[data['Car']].append(data['Value_in_US'])

works

Answer 3

You can use itertools.groupby to do this easily

resultset = [
 {'Car': 'Aston Martin DB Nine', 'Value_in_US': '10'},
 {'Car': 'Aston Martin DB Nine', 'Value_in_US': '11'},
 {'Car': 'Aston Martin DB Nine', 'Value_in_US': '10'},
 {'Car': 'Aston Martin DB Nine', 'Value_in_US': '14'},
 {'Car': 'Lambo ', 'Value_in_US': '11'},
 {'Car': 'Porshe Nine', 'Value_in_US': '12'},
 {'Car': 'Porshe Nine', 'Value_in_US': '10'}]

from itertools import groupby
f = lambda d: d['Car']
res = {k:[d2['Value_in_US'] for d2 in g] for k,g in groupby(sorted(resultset, key=f), f)}
print(res)

Outout

{'Aston Martin DB Nine': ['10', '11', '10', '14'],
 'Lambo ': ['11'],
 'Porshe Nine': ['12', '10']}

Answer 4

Dict/list comprehension should do the trick if you like inline expressions,

resultset=[
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"10",
    },
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"11",
    },
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"10",
    },
    {
       "Car":"Aston Martin DB Nine",
       "Value_in_US":"14",
    },
    {
       "Car":"Lambo ",
       "Value_in_US":"11",
    },
    {
       "Car":"Porshe Nine",
       "Value_in_US":"12",
    },
    {
       "Car":"Porshe Nine",
       "Value_in_US":"10",
    },
]

#init with empty list for each cars
result = {dic['Car']:[] for dic in resultset} 

#append the value to each car entry
[result[dic['Car']].append(dic['Value_in_US']) for dic in resultset]
print(result)

>>>> {'Aston Martin DB Nine': ['10', '11', '10', '14'], 'Lambo ': ['11'], 'Porshe Nine': ['12', '10']}

Here is a good guide on medium to start with dictionary comprehension.