how to convert pandas dataframe to dictionary like specified

Question

this is the data frame:

     course_id  weight
0          1      10
1          1      40
2          1      50
3          2      40
4          2      60
5          3      90
6          3      10

want to convert it to a dictionary like:

{1 : [10,40,50] , 2:[40,60] , 3 :[90,10]}

df = pd.read_csv(tests) 
df = df[['course_id','weight']]
print(df)

When sharing dataframe, please give python code to build it, so everyone has not to do it — azro, Nov 07 '21 at 16:24
Does this help? https://stackoverflow.com/a/29876239/2681662 — MSH, Nov 07 '21 at 16:25
If we don't have the csv that doesn't help ^^ paste an output of `df.to_dict()` for example — azro, Nov 07 '21 at 16:26

score 0 · Answer 1 · answered Nov 07 '21 at 16:27

You need to groupby course_id column, then keep weight, put values in lists, and use to_dict() to get final structure

import pandas as pd

df = pd.DataFrame({'course_id': {0: 1, 1: 1, 2: 1, 3: 2, 4: 2, 5: 3, 6: 3},
                   'weight': {0: 10, 1: 40, 2: 50, 3: 40, 4: 60, 5: 90, 6: 10}})
result = df.groupby("course_id")['weight'].apply(list).to_dict()
print(result)  # {1: [10, 40, 50], 2: [40, 60], 3: [90, 10]}

how to convert pandas dataframe to dictionary like specified

1 Answers1