How to convert csv to dictionary of dictionaries in python?

Question

I have a CSV file shown below.I need to convert CSV to dictionary of dictionaries using python.

 userId movieId rating
1         16    4
1         24    1.5
2         32    4
2         47    4
2         50    4
3        110    4
3        150    3
3        161    4
3        165    3

The output should be like shown below

dataset={'1':{'16':4,'24':1.5},
         '2':{'32':4,'47':4,'50':4},
         '3':{'110':4,'150':3,'161':4,'165':3}}

Please let me know how to do this. Thanks in advance

any attempts at solving this so far? If so, please share them by editing your question. If not, please attempt something before asking a question. — Dimitris Fasarakis Hilliard, Nov 07 '16 at 13:15

score 2 · Accepted Answer · edited May 23 '17 at 12:24

You are looking for nested dictionaries. Implement the perl's autovivification feature in Python (the detailed description is given here). Here is a MWE.

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import csv

class AutoVivification(dict):
    """Implementation of perl's autovivification feature."""
    def __getitem__(self, item):
        try:
            return dict.__getitem__(self, item)
        except KeyError:
            value = self[item] = type(self)()
            return value

def main():
    d = AutoVivification()
    filename = 'test.csv'
    with open(filename, 'r') as f:
        reader = csv.reader(f, delimiter=',')
        next(reader)        # skip the header
        for row in reader:
            d[row[0]][row[1]] = row[2]

    print(d)
    #{'1': {'24': '1.5', '16': '4'}, '3': {'150': '3', '110': '4', '165': '3', '161': '4'}, '2': {'32': '4', '50': '4', '47': '4'}}

if __name__ == '__main__':
    main()

The content of test.csv,

userId,movieId,rating
1,16,4
1,24,1.5
2,32,4
2,47,4
2,50,4
3,110,4
3,150,3
3,161,4
3,165,3

Hai, In above code "d" is not saving to proceed further. – akhil s Nov 08 '16 at 05:32 — akhil s, Nov 08 '16 at 05:32

score 0 · Answer 2 · answered Nov 07 '16 at 13:30

0

import numpy as np

col1,col2,col3 = np.loadtxt('test2.csv',delimiter=',',skiprows=1,unpack=True,dtype=int)

dataset = {}

for a,b,c in zip(col1,col2,col3):
    if str(a) in dataset:
        dataset[str(a)][str(b)]=str(c)
    else:
        dataset[str(a)]={str(b):str(c)}
print(dataset)

This should do. The example file above looks like a tsv (tab separated value). If so, remove the delimiter flag in my example.

answered Nov 07 '16 at 13:30

Jannis

321
1
3
8

Thank you so much, it's working but I am not getting decimal points. – akhil s Nov 07 '16 at 15:57

score 0 · Answer 3 · answered Nov 07 '16 at 13:35

import csv
dataset = dict()
with open("file_name", "rb") as csv_file:
    data = csv.DictReader(csv_file)
    for row in data:
        old_data = dataset.get(row["userId"], None)

        if old_data is None:
            dataset["userId"] = {row["movieId"]: row["rating"] }
        else:
            old_data[row["movieId"]] = row["rating"]
            dataset[row["userId"]] = old_data

How to convert csv to dictionary of dictionaries in python?

3 Answers3

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