python解决排列组合，,笛卡尔积：itert

python解决排列组合，,笛卡尔积：itert

笛卡尔积：itertools.product(*iterables[, repeat])

import itertoolsfor i in itertools.product(‘BCDEF‘, repeat = 2):    print(‘‘.join(i),end=",")print(‘\n‘)# 输出 BB BC BD BE BF CB CC CD CE CF DB DC DD DE DF EB EC ED EE EF FB FC FD FE FF

　　两个元组进行笛卡尔积：

import itertoolsa = (1, 2)b = (‘A‘, ‘B‘, ‘C‘)c = itertools.product(a,b)for i in c:    print(i,end=",")# 输出(1, ‘A‘) (1, ‘B‘) (1, ‘C‘) (2, ‘A‘) (2, ‘B‘) (2, ‘C‘)

排列：itertools.permutations(iterable[, r])

import itertoolsfor i in itertools.permutations(‘BCD‘, 2):    print(‘‘.join(i),end=",")# 输出 BC BD CB CD DB DCprint(‘\n‘)

组合：itertools.combinations(iterable, r)

import itertoolsfor i in itertools.combinations(‘BCDEF‘, 2):    print(‘‘.join(i),end=" ")# 输出 BC BD BE BF CD CE CF DE DF EFprint(‘\n‘)

组合（包含自身重复）：itertools.combinations_with_replacement(iterable, r)

import itertoolsfor i in itertools.combinations_with_replacement(‘ABC‘, 3):    print (‘‘.join(i),end=‘ ‘)# 输出 AAA AAB AAC ABB ABC ACC BBB BBC BCC CCCprint(‘\n‘)

举例

‘BCDEF五个字母组合问题‘import itertoolsprint("1个组合：")for i, val in enumerate(list(itertools.combinations(‘BCDEF‘, 1))):    print("序号：%s   值：%s" % (i + 1, ‘‘.join(val)))print("2个组合：")for i, val in enumerate(list(itertools.combinations(‘BCDEF‘, 2))):    print("序号：%s   值：%s" % (i + 1, ‘‘.join(val)))print("3个组合：")for i, val in enumerate(list(itertools.combinations(‘BCDEF‘, 3))):    print("序号：%s   值：%s" % (i + 1, ‘‘.join(val)))print("4个组合：")for i, val in enumerate(list(itertools.combinations(‘BCDEF‘, 4))):    print("序号：%s   值：%s" % (i + 1, ‘‘.join(val)))print("5个组合：")for i, val in enumerate(list(itertools.combinations(‘BCDEF‘, 5))):    print("序号：%s   值：%s" % (i + 1, ‘‘.join(val)))

python解决排列组合