Python extract values in JSON array to form a new key-value pair-CodePudding

Given an array of JSON objects as:

arr=[{"id": "abc", "value": "123"}, {"id": "xyz", "value": "456"}]

I would like to output a single JSON object like:

new_arr={"abc":123,"xyz":456}

Currently I can extract the elements like arr[0]['id'] but I am wondering what's the one-liner or better way to form the output.

CodePudding user response：

A one-liner to extract the ids and values would be like this:

new_arr = {item['id']: int(item['value']) for item in arr}

as the arr object contains the value as a str you need to convert it to an int(). The rest of the one line similar to a list comprehension with dict as the base element to add to, thereby being a dict comprehension. Though this assumes that all dicts have a id and value combination (which is unknown from your data and am assuming that they always have an id and value)

CodePudding user response：

One alternative, showing the versatility of itemgetter:

from operator import itemgetter

arr = [{"id": "abc", "value": "123"}, {"id": "xyz", "value": "456"}]

# itemgetter creates a function to extract the values at id and value
pair = itemgetter("id", "value")

# use map to apply the function to each element of arr
d = dict(map(pair, arr))

# print the result
print(d)

Output

{'abc': '123', 'xyz': '456'}

CodePudding user response：

One line solution can be this:

new_arr = {item['id']: int(item['value']) for item in arr}

Or you can use itemgetter opertaror:

new = dict(map(itemgetter("id", "value"), arr))

CodePudding user response：

Minimum code I think

arr = [{"id": "abc", "value": "123"}, {"id": "xyz", "value": "456"}]
json = {item['id']: item['value'] for item in arr}
print(json)

result:

{'abc': '123', 'xyz': '456'}