在迭代时将键添加到int的defaultdict

Question

The script needs to read input from a text/csv file but as soon as I try and implement the functionality, everything breaks.

Here is my code:

from collections import defaultdict
#from csv import reader

data = """Lions 3, Snakes 3
Tarantulas 1, FC Awesome 0
Lions 1, FC Awesome 1
Tarantulas 3, Snakes 1
Lions 4, Grouches 0"""

# with open('sample_input.csv') as data:
#     csv = reader(data)
#     list_csv = [line.rstrip('\n') for line in data]

data_list = data.splitlines()


def splitter(row):
    left_team, right_team = row.split(',')
    return {
        'left': left_team[:-2].strip(),
        'left_score': int(left_team[-2:].strip()),
        'right': right_team[:-2].strip(),
        'right_score': int(right_team[-2:].strip())
    }


data_dicts = [splitter(row) for row in data_list]


team_scores = defaultdict(int)
for game in data_dicts:
    if game['left_score'] == game['right_score']:
        team_scores[game['left']] += 1
        team_scores[game['right']] += 1
    elif game ['left_score'] > game['right_score']:
        team_scores[game['left']] += 3
    else:
        team_scores[game['right']] += 3
    print(team_scores)

teams_sorted = sorted(team_scores.items(), key=lambda team: team[1], reverse=True)


# for line in teams_sorted:
#     print(line)

Also, the expected output that I need to have is:

1. Tarantulas, 6 pts
2. Lions, 5 pts
3. FC Awesome, 1 pt
3. Snakes, 1 pt
4. Grouches, 0 pts

I just can't seem to figure out how to get to this step. I checked most parts of my code with print statements and it seems the dictionary is working correctly but it is not printing the last team and it's score (Grouches, 0 pts).

I am currently getting this output:

('Tarantulas', 6)
('Lions', 5)
('Snakes', 1)
('FC Awesome', 1)

Any help would be greatly appreciated!

Answer 1

have you tried the CSV python lib? Extracted from the doc ( https://docs.python.org/3/library/csv.html ):

import csv
with open('data.csv', newline='') as csvfile:
    spamreader = csv.reader(csvfile, delimiter=' ', quotechar='|')
    for row in spamreader:
        print(', '.join(row))

Answer 2

Well done for getting this far. You have managed to implement the logic, but have got stuck with a specific behaviour of defaultdict . There are 2 main points to note:

1. If a key is not initialized with defaultdict , it won't be added to the dictionary. You can do this simply by adding 0 to a non-initialized key.
2. For the specific formatting you require, you can use enumerate in a loop after sorting.

Putting these together, amend your loop as below:

for game in data_dicts:
    if game['left_score'] == game['right_score']:
        team_scores[game['left']] += 1
        team_scores[game['right']] += 1
    elif game ['left_score'] > game['right_score']:
        team_scores[game['left']] += 3
        team_scores[game['right']] += 0
    else:
        team_scores[game['left']] += 0
        team_scores[game['right']] += 3

Then use enumerate in a loop. You can use operator.itemgetter and f-strings (the latter in Python 3.6+) to make your logic cleaner:

from operator import itemgetter

teams_sorted = sorted(team_scores.items(), key=itemgetter(1), reverse=True)

for idx, (team, score) in enumerate(teams_sorted, 1):
    print(f'{idx}. {team} {score} pts')

1. Tarantulas 6 pts
2. Lions 5 pts
3. Snakes 1 pts
4. FC Awesome 1 pts
5. Grouches 0 pts

Answer 3

To the code breaking on adding CSV. CSV reader does the split(',') for you. So your left_team = row[0] and right_team = row[1]

So your code changes to something like

def spliter(row):
    left_team, right_team = row
    return {
        'left': left_team[:-2].strip(),
        'left_score': int(left_team[-2:].strip()),
        'right': right_team[:-2].strip(),
        'right_score': int(right_team[-2:].strip())
    }

with open('data.csv') as data_obj:
    reader = csv.reader(data_obj)
    data_dicts = [splitter(row) for row in reader]

You can go for plaintext reading if you want to manually split(',') .

with open('data.csv') as data_obj:
    data_list = [line.rstrip('\n') for line in data_obj.readlines()]