How to merge JSON array and an array

Question

I have 2 arrays as below:

array 1:

[
    {"name": "A", "class" : "1"},
    {"name": "B", "class" : "2"},
    {"name": "C", "class" : "3"}
]

array 2:

[ "A","B"]

I wanna merge 2 arrays, and my expected result:

[
    {"name": "A", "class" : "1"},
    {"name": "B", "class" : "2"}
]

Any suggestion is appreciated

What I found so far:

Possible duplicate of Python: filter list of list with another list — user8060120
– user8060120, Commented Apr 9, 2019 at 14:35
This question doesn't seem to be related to JSON, unless you are getting these values as a string. Your first value is just a normal Python dictionary. — Christoph Burschka
– Christoph Burschka, Commented Apr 9, 2019 at 14:37
This isn't a merge; it's a filter. You want to select the dicts whose name value appears in list 2. JSON is irrelevant, except as the source of one or both lists; the filtering doesn't care how the lists get defined. — chepner
– chepner, Commented Apr 9, 2019 at 14:39

gmds · Accepted Answer · 2019-04-09 15:01:50Z

5

Just use a list comprehension:

first = [
         {"name": "A", "class" : "1"},
         {"name": "B", "class" : "2"},
         {"name": "C", "class" : "3"}
]

second = ['A', 'B']

result = [d for d in first if d['name'] in second]
print(result)

Output:

[{'name': 'A', 'class': '1'}, {'name': 'B', 'class': '2'}]

In the case raised in the comments:

from operator import itemgetter

first = [
         {"name": "A", "class" : "1"},
         {"name": "B", "class" : "2"},
         {"name": "C", "class" : "3"}
]

second = [
         {"name": "A"},
         {"name": "B"}
]

result = [d for d in first if d['name'] in map(itemgetter('name'), second)]
print(result)

Output:

[{'name': 'A', 'class': '1'}, {'name': 'B', 'class': '2'}]

edited Apr 9, 2019 at 15:01

answered Apr 9, 2019 at 14:34

gmds

20k4 gold badges37 silver badges65 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Phong Vu Over a year ago

if the 2nd array is a JSON array : [{'name': 'A'}, {'name':'B'}]. How to achieve the result ?

gmds Over a year ago

@PhongVu [d for d in first if d in second] will work fine.

chepner Over a year ago

@PhongVu A JSON array is just a string that can be decoded into some native data structure. [{'name': 'A'}, {'name':'B'}] is an ordinary Python list consisting of dicts that was initialized from a JSON array.

Phong Vu Over a year ago

Thanks @chepner for making clear the word "JSON array"

Phong Vu Over a year ago

@gmds: I tried your suggestion, it just returns an empty array []

|

Collectives™ on Stack Overflow

How to merge JSON array and an array

1 Answer 1

7 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

7 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related