CODEWITHSUNDEEP
pythonlistdictionary
Em Bass
Em Bass

Reputation: 33

Creating a list of lists from dictionary values

I need to filter this data by the month. I need the results to a be a list of lists like lst = [[92], [86], [89]]

This is what I have tried:

data_dict = [
    {
        "student": "john",
        "subject": "english",
        "grade": "A",
        "marks": 92,
        "assessement type": "exam",
        "date": [2, 1, 2021],
    },
    {
        "student": "john",
        "subject": "math",
        "grade": "B",
        "marks": 86,
        "assessement type": "essay",
        "date": [2, 3, 2021],
    },
    {
        "student": "john",
        "subject": "history",
        "grade": "B",
        "marks": 89,
        "assessement type": "presentation",
        "date": [22, 2, 2021],
    },
]

lst = []
for x in data_dict:
    for i in range(1, 13):
        if x["date"][1] == i:
            lst.append(x["marks"])

output:

lst = [92, 86, 89]

How do I make the results a list of lists?

ETA. I need to learn how to do these things without an external library ready for exams in a few weeks.

Upvotes: 0

Views: 52

Answers (2)

Vignesh Shankar
Vignesh Shankar

Reputation: 19

lst = []
for i in range(1,13):
    templst = []
    for x in data_dict:
        if x["date"][1]==i:
            templst.append(x["marks"])
    lst.append(templst) 


lst

out: [[92, 93, 89], [89], [86], [], [], [], [], [], [], [], [], []]

Upvotes: 0

AKX
AKX

Reputation: 168976

You'll probably have a better time gathering the grades up into a dict per month, and then if you need a list of lists with all months, no matter if they have grades, that's easy enough:

from collections import defaultdict

data_dict = [
    {
        "student": "john",
        "subject": "english",
        "grade": "A",
        "marks": 92,
        "assessement type": "exam",
        "date": [2, 1, 2021],
    },
    {
        "student": "john",
        "subject": "math",
        "grade": "B",
        "marks": 86,
        "assessement type": "essay",
        "date": [2, 3, 2021],
    },
    {
        "student": "john",
        "subject": "history",
        "grade": "B",
        "marks": 89,
        "assessement type": "presentation",
        "date": [22, 2, 2021],
    },
]

grades_by_month = defaultdict(list)

for x in data_dict:
    grades_by_month[x["date"][1]].append(x["marks"])

grades_every_month = [grades_by_month[x] for x in range(1, 13)]
print(grades_every_month)

prints out

[[92], [89], [86], [], [], [], [], [], [], [], [], []

(grades_by_month will look like {1: [92], 3: [86], 2: [89]}.)

Upvotes: 1

Related Questions