How to create a doubly-nested dict from CSV?-CodePudding

I am trying to read a Financial CSV with Python, and the data looks like this:

Company1;2018;12345;67890;
Company1;2019;34242;12313;
Company2;2018;12412;32423;
Company3;2017;12314;23554;
...

What I am searching for is a function that give me following result after reading this CSV:

Dict2 = {
   Company1: { 2018: { Costs: 123, employes: 1231}
               2019: { Costs: 231, employes: 1321}}
   Company2: { 2019: { Costs: 123, employes: 1231}
   Company3: { 2019: { Costs: 123, employes: 1231}
        }

I am processing the CSV like this:

file2 = open(pfad_ordner   "\daten\standortdaten\FirmenBilanz.csv", "r")

reader = csv.reader(file2, delimiter =";")

Dict2 = {}

for row in reader:
    Dict2[row[0]] = {"Jahr":row[2], "Ort":row[1], "Mitarbeiter_gewerblich": row[3]}

if i do it this way, python ignores the row with same company name. or lets better say, it updates the dictionary so only one row got stored per company key.

CodePudding user response：

The defaultdict class from the collections module can help you out.

You'll create Dict2 to be a dictionary that's meant to store other dictionaries:

Dict2 = defaultdict(dict)

Now, you can supply the company's name as a key, and give that key a value that is your "sub dict" of the year with the other values as a dictionary... all in one statement:

Dict2['Foo, inc.']['2018'] = {'Cost': 23, 'Employees': 9}

Here it is put together:

import csv
from collections import defaultdict

file2 = open(pfad_ordner   "\daten\standortdaten\FirmenBilanz.csv", "r")

reader = csv.reader(file2, delimiter =";")

Dict2 = defaultdict(dict)

for row in reader:
    name = row[0]
    year = row[1]
    Dict2[name][year] = { 'other values from row' }