Itertools product without repeating duplicates

问题

from itertools import product
teams = ['india', 'australia', 'new zealand']
word_and = ['and']
tmp = '%s %s %s'
items = [teams, word_and, teams]
print(list(tmp % a for a in list(product(*items))))

prints:

['india and india',
 'india and australia',
 'india and new zealand',
 'australia and india',
 'australia and australia',
 'australia and new zealand',
 'new zealand and india',
 'new zealand and australia',
 'new zealand and new zealand']

How to:

1. avoid the same name repeating in a single sentence (india and india)
2. generate only one combination (either india and australia or australia and india)

http://pythonfiddle.com/product-without-matching-duplicates

回答1:

You should use itertools.combinations like this

>>> from itertools import combinations
>>> teams = ['india', 'australia', 'new zealand']
>>> [" and ".join(items) for items in combinations(teams, r=2)]
['india and australia', 'india and new zealand', 'australia and new zealand']

But for this simple case, you can run two loops, like this

>>> ["%s and %s" % (t1, t2) for i, t1 in enumerate(teams) for t2 in teams[i + 1:]]
['india and australia', 'india and new zealand', 'australia and new zealand']

来源：https://stackoverflow.com/questions/29314372/itertools-product-without-repeating-duplicates