def test_combinations_invert_n_m(two_ints):
"""
nCm = nCn-m
n!/(n-m)!m! = n!/m!(n-m)!
"""
num = two_ints[0]
choose = two_ints[1]
n_choose_m = stats.combinations(num, choose=choose)
n_choose_n_minus_m = stats.combinations(num, choose=num - choose)
assert n_choose_m == n_choose_n_minus_m
def test_combinations_versus_reference_implementation(two_ints):
num = two_ints[0]
choose = two_ints[1]
result = stats.combinations(num, choose=choose)
reference = stats._combinations_reference(num, choose=choose)
assert result == reference
def test_combinations_choose_one(integer):
assert stats.combinations(integer, choose=1) == integer
def test_combinations_choose_zero(integer):
assert stats.combinations(integer, choose=0) == 1
def test_combinations_choose_all(integer):
assert stats.combinations(integer, choose=integer) == 1
def test_combinations_choose_none(integer):
assert stats.combinations(integer) == 1