Is it possible to write a Dictionary of Dictionaries to a CSV file?

Question

The dictionary format I'm referring to looks like this (FYI, these are just football players):

player_list = {
    'Shkodran Mustafi': {'first': 'Shkodran', 'last': 'Mustafi', 'team': 'Arsenal'},
    'Héctor Bellerín': {'first': 'Héctor', 'last': 'Bellerín', 'team': 'Arsenal'},
    'Sead Kolasinac': {'first': 'Sead', 'last': 'Kolasinac', 'team': 'Arsenal'}
    }

Is it possible to use this dictionary to write something like the table below to a CSV?

First Name:    Last Name:     Team: 

Shkodran       Mustafi        Arsenal
Héctor         Bellerín       Arsenal
Sead           Kolasinac      Arsenal

Any help on how to achieve this would be greatly appreciated! THANK YOU!

Answer 1

If you really want the columns from the inner dictionaries written to a CSV file, it can be done very easily with Pandas.

player_list = {
    'Shkodran Mustafi': {'first': 'Shkodran', 'last': 'Mustafi', 'team': 'Arsenal'},
    'Héctor Bellerín': {'first': 'Héctor', 'last': 'Bellerín', 'team': 'Arsenal'},
    'Sead Kolasinac': {'first': 'Sead', 'last': 'Kolasinac', 'team': 'Arsenal'},}
import pandas as pd
df = pd.DataFrame(player_list).T
df.columns = ['First Name', 'Last Name', 'Team']
df.to_csv('test.csv', index=False)

Will produce the CSV equivalent of the table that you posted in your question:

First Name,Last Name,Team
Shkodran,Mustafi,Arsenal
Héctor,Bellerín,Arsenal
Sead,Kolasinac,Arsenal

Answer 2

So basically iterating the dictionary and putting it in.csv format?

player_list = {
    'Shkodran Mustafi': {'first': 'Shkodran', 'last': 'Mustafi', 'team': 'Arsenal'},
    'Héctor Bellerín': {'first': 'Héctor', 'last': 'Bellerín', 'team': 'Arsenal'},
    'Sead Kolasinac': {'first': 'Sead', 'last': 'Kolasinac', 'team': 'Arsenal'}}

keys = ['first', 'last', 'team']

with open("data.csv", 'w') as wf:
    wf.write("First Name:,Last Name:,Team:\n")
    for k, v in player_list.items():
        to_write = []
        for key in keys:
             to_write.append(str(v[key]))
        wf.write(','.join(to_write) + '\n')

Answer 3

In this case, you don't even need to worry about the fact that it's a dictionary of dictionaries. You're only ever outputting the "inner" dictionary anyway, so you can do something like this:

player_list = {
'Shkodran Mustafi': {'first': 'Shkodran', 'last': 'Mustafi', 'team': 'Arsenal'},
'Héctor Bellerín': {'first': 'Héctor', 'last': 'Bellerín', 'team': 'Arsenal'},
'Sead Kolasinac': {'first': 'Sead', 'last': 'Kolasinac', 'team': 'Arsenal' }
}

with open('output.csv', 'w') as writer:
    writer.write("First Name:,Last Name:,Team:\n")
    for key, value in player_list.items():
        writer.write(value['first'] + ',' + value['last'] + ',' + value['team'] + '\n')

In this case, there are only 3 values, so I just used string concatenation, but if you're doing more values, you may want to try something like what @tgikal is doing.

Answer 4

CSV is a format which can represent any hash of hashes or if I guess correctly that you are using Python dictionary of dictionaries.

You need to write the correct parser

One way would be to use a different different delimiter to represent nested hashes eg brackets {

{,Shkodran Mustafi,{,first,Shkodran,last,Mustafi,team,Arsenal,},}

I suggest you use json, yaml or hocon they are easier on the human eye

Answer 5

An object you may find useful is csv.DictWriter : https://docs.python.org/2/library/csv.html#csv.DictWriter

example usage:

import csv

player_list = {
    'Shkodran Mustafi': {'first': 'Shkodran', 'last': 'Mustafi','team': 'Arsenal'},
    'Héctor Bellerín': {'first': 'Héctor', 'last': 'Bellerín','team': 'Arsenal'},
    'Sead Kolasinac': {'first': 'Sead', 'last': 'Kolasinac', 'team': 'Arsenal'}
}

with open("player_data.csv", 'w') as fp:
    writer = csv.DictWriter(fp, fieldnames=['first', 'last', 'team'])
    writer.writeheader()
    for player_name, player_info in player_list.items():
        writer.writerow(player_info)