CODEWITHSUNDEEP
pythonlist
user1981437
user1981437

Reputation: 93

Shuffle and match list elements so that no duplicate matches can be made

i have list of names that i want to match for a tennis competition. The games are taking place once a week and everyone should have a new opponent each week till all pairings have been made.

To create 2 people combinations with all the players I did the following:

from itertools import combinations 

names = [‘ben’,
         ‘josh’,
         ‘jessy’,
         ‘natalia’]

result = [[a + ‘-‘ + b] for a, b in combinations(names, 2)]

This gives the following:

[['ben - josh'],
 ['ben - jessy'],
 [‘ben - natalia'],
 ['josh - jessy'],
 ['josh - natalia'],
 ['jessy - natalia']]

The last part is to match each player with someone who they’ve never played before. In order to do this i did the following:


for i, j in zip(range(int(len(result)/2)), (reversed(range(int(len(result) /2),len(result))))):

    print(result[i], result[j]

This way each player plays with someone new each time. The result is:



['ben - josh'] ['jessy - natalia']

['ben - jessy'] ['josh - natalia']

['ben - natalia'] ['josh - jessy']

How I can extend the following to a much bigger list of players ? Lets say 100+ ? Is there any better way of doing this ? Also, what if the list of players has odd number of players ? Thanks for your help with this.

Upvotes: 0

Views: 34

Answers (1)

Adon Bilivit
Adon Bilivit

Reputation: 27324

Even if your list contains 100+ names, the performance difference will be negligible.

An odd number of names is managed correctly using similar logic.

The second phase of your process can be simplified as follows:

from itertools import combinations

names = ["ben", "josh", "jessy", "natalia", "dan"]

pairs = list(combinations(names, 2))

m = len(pairs) // 2

for a, b in zip(pairs[:m], reversed(pairs)):
    print(a, b)

('ben', 'josh') ('natalia', 'dan')
('ben', 'jessy') ('jessy', 'dan')
('ben', 'natalia') ('jessy', 'natalia')
('ben', 'dan') ('josh', 'dan')
('josh', 'jessy') ('josh', 'natalia')

Upvotes: 0

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