Create a dictionary from a csv file where a specific column is the key and the rows are the values in Python

Question

I have a csv file formatted as below:

jersey number,   position,   name,   birth_date,    birth_city,   years_in_nba,   team
23           ,     SF    ,   Lebron,  12/30/84 ,     Akron    ,      19      ,   Lakers
30           ,     PG    ,   Curry,   03/14/88 ,     Akron    ,      13      ,   Warriors
34           ,     PF    ,   Giannis, 08/26/89 ,     Athens    ,      8      ,   Bucks

My goal is to be able to group the rows by position where the key is the different positions and and the values are a list of player info having in common the same position like below:

{
"SF": [{..player1..}, {..player2..}],
"PF": [{..player1..}, {..player2..}],
"SG": [{..player1..}, {..player2..}],
"PG": [{..player1..}, {..player2..}],
}

This is what I have so far:

positions = {}
def players_position():
with open(filename, 'r') as file_obj:
    dict_reader = DictReader(file_obj, delimiter=",")
    for row in dict_reader:
        positions[row["position"]] = row
return positions

print(players_position())

with the code as it is, the current value will always override the previous one. I don’t want that. I want to have a list where we can keep appending player info like displayed above.

Asked By: Nasser

||

Source

Answer 1

Try this

positions = {}

def players_position():
    with open(filename, 'r') as file_obj:
        dict_reader = DictReader(file_obj, delimiter=",")
        for row in dict_reader:
            position = row["position"]
            if position in positions:
                positions[position].append(row)
            else:
                positions[position] = [row]
    return positions

print(players_position())

The function checks if the position is already in positions. If it is, we simply append the current row to the list of players already in that position. If it is not, we create a new list containing the current row and assign it to positions[position].

Note that, this is based on your answer.

Answered By: Isa Kurbanov

Answer 2

Here you go. I originally tried basing this off what you had, but because the data when split in the CSV raw data ends up with a bunch of whitespace padding, I did a little extra work to clean up the keys/values.

import csv

CSV = """
# jersey number,   position,   name,   birth_date,    birth_city,   years_in_nba,   team
# 23           ,     SF    ,   Lebron,  12/30/84 ,     Akron    ,      19      ,   Lakers
# 30           ,     PG    ,   Curry,   03/14/88 ,     Akron    ,      13      ,   Warriors
# 34           ,     PF    ,   Giannis, 08/26/89 ,     Athens    ,      8      ,   Bucks
"""


def main():
    players = [player for player in csv.DictReader(CSV.splitlines())]
    # gives me:

    """
    {None: ['# jersey number', '   position', '   name', '   birth_date', '    birth_city', '   years_in_nba', '   team']}
    {None: ['# 23           ', '     SF    ', '   Lebron', '  12/30/84 ', '     Akron    ', '      19      ', '   Lakers']}
    {None: ['# 30           ', '     PG    ', '   Curry', '   03/14/88 ', '     Akron    ', '      13      ', '   Warriors']}
    {None: ['# 34           ', '     PF    ', '   Giannis', ' 08/26/89 ', '     Athens    ', '      8      ', '   Bucks']}
    """

    # strip the keys because extra whitespace, and because of how DictReader makes arrays, we have to do this:
    keys = [k.strip() for k in [v for v in players.pop(0).values()][0]]

    # then let's gather the players and strip the values so they don't have unnecessary spaces
    players = [[p.strip() for p in list(p.values())[0]] for p in [v for v in players]]

    # and combine (zip) the keys and values to make a dictionary
    players_list = [dict(zip(keys, p)) for p in players]

    # this gives me:
    """
    {'# jersey number': '# 23', 'position': 'SF', 'name': 'Lebron', 'birth_date': '12/30/84', 'birth_city': 'Akron', 'years_in_nba': '19', 'team': 'Lakers'}
    {'# jersey number': '# 30', 'position': 'PG', 'name': 'Curry', 'birth_date': '03/14/88', 'birth_city': 'Akron', 'years_in_nba': '13', 'team': 'Warriors'}
    {'# jersey number': '# 34', 'position': 'PF', 'name': 'Giannis', 'birth_date': '08/26/89', 'birth_city': 'Athens', 'years_in_nba': '8', 'team': 'Bucks'}
    """

    # last, create a dictionary of lists grouping by position using a list comprehension
    # you could do this in a for loop, but we're writing python, after all...
    players_by_position = {
        position: [
        player for player in players_list if player['position'] == position
      ] for position in set([player['position'] for player in players_list])
    }
    
    return players_by_position

    """
    {
      'SF': [
        {
          '# jersey number': '# 23', 
          'position': 'SF', 
          'name': 'Lebron', 
          'birth_date': '12/30/84', 
          'birth_city': 'Akron', 
          'years_in_nba': '19', 
          'team': 'Lakers'
        }
      ], 
      'PG': [
        {
          '# jersey number': '# 30', 
          'position': 'PG', 
          'name': 'Curry', 
          'birth_date': '03/14/88', 
          'birth_city': 'Akron', 
          'years_in_nba': '13', 
          'team': 'Warriors'
        }
      ], 
      'PF': [
        {
          '# jersey number': '# 34', 
          'position': 'PF', 
          'name': 'Giannis', 
          'birth_date': '08/26/89', 
          'birth_city': 'Athens', 
          'years_in_nba': '8', 
          'team': 'Bucks'
        }
      ]
    }
    """

if __name__ == "__main__":
    print(main())

Answered By: brandonscript

Create a dictionary from a csv file where a specific column is the key and the rows are the values in Python

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