Adding a Key:Values in list of dictionaries in Python3

Question

I have a list of dictionary as below

my_list = [
{'Overall': 'PASS', 'subjects': 4, 'student_id': '90e263', 'data': {'Social': 71, 'Science': 55, 'Maths': 99, 'French': 79}}, 
{'Overall': 'FAIL', 'subjects': 4, 'student_id': '90e264', 'data': {'Social': 56, 'Science': 18, 'Maths': 61, 'French': 49}}
]

And I would like to add a key:value pair 'class': 'Third Standard' to all the dictionaries inside the list making the resultant list look like below -

my_list = [
{'Overall': 'PASS', 'subjects': 4, 'student_id': '90e263', 'data': {'Social': 71, 'Science': 55, 'Maths': 99, 'French': 79}, 'class': 'Third Standard'}, 
{'Overall': 'FAIL', 'subjects': 4, 'student_id': '90e264', 'data': {'Social': 56, 'Science': 18, 'Maths': 61, 'French': 49}, 'class': 'Third Standard'}
]

Note - This is a sample list with just two dictionaries but I've got 1000s of dictionaries in my actual list.

Can someone please help me with best way to update all dictionaries inside the list?

Iterate over the list, and set the `'class'` key of each item in the list to `'Third Standard'`. There is no _"best way"_ without more context — Pranav Hosangadi, Jan 11 '23 at 22:51

BrokenBenchmark · Accepted Answer · 2023-01-11T22:58:40.897

1

You can use the dictionary union operator with a list comprehension:

[entry | {"class": "Third Standard"} for entry in my_list]

Alternatively, if you'd like to modify the dictionaries in-place, you can use a simple for loop:

for entry in my_list:
    entry["class"] = "Third Standard"

This produces:

[
    {
        "Overall": "PASS",
        "subjects": 4,
        "student_id": "90e263",
        "data": {
            "Social": 71,
            "Science": 55,
            "Maths": 99,
            "French": 79
        },
        "class": "Third Standard"
    },
    {
        "Overall": "FAIL",
        "subjects": 4,
        "student_id": "90e264",
        "data": {
            "Social": 56,
            "Science": 18,
            "Maths": 61,
            "French": 49
        },
        "class": "Third Standard"
    }
]

edited Jan 11 '23 at 22:58

answered Jan 11 '23 at 22:52

BrokenBenchmark

18,126
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There's really no point in creating a whole new list with all new dictionaries when OP just needs to modify their originals in a simple loop. – Pranav Hosangadi Jan 11 '23 at 22:53
Fair point. I've updated my answer. – BrokenBenchmark Jan 11 '23 at 22:54
1

Please also try looking for duplicates before adding an answer https://stackoverflow.com/questions/14071038/add-an-element-in-each-dictionary-of-a-list-list-comprehension – Pranav Hosangadi Jan 11 '23 at 22:57

score 0 · Answer 2 · answered Jan 11 '23 at 22:56

0

Just iterate the list and add value to dictionary:

my_list = [
    {'Overall': 'PASS', 'subjects': 4, 'student_id': '90e263', 'data': {'Social': 71, 'Science': 55, 'Maths': 99, 'French': 79}}, 
    {'Overall': 'FAIL', 'subjects': 4, 'student_id': '90e264', 'data': {'Social': 56, 'Science': 18, 'Maths': 61, 'French': 49}}
]

for d in my_list:
    d["class"] = "Third Standard"

answered Jan 11 '23 at 22:56

Guru Stron

102,774
10
95
132

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Please try looking for duplicates before adding an answer https://stackoverflow.com/questions/14071038/add-an-element-in-each-dictionary-of-a-list-list-comprehension Such basic questions are bound to have duplicates – Pranav Hosangadi Jan 11 '23 at 22:58

Adding a Key:Values in list of dictionaries in Python3

2 Answers2