Python：替换列表项并产生所有可能的排列

Question

我正在尝试为部分莫尔斯电码实现莫尔斯解码。例如，莫尔斯电码中单词 TEST 的表示是 ['-','.','...','-'] 但是如果第一个每个莫尔斯电码字符串的字符都丢失并由 x 表示，那么 TEST 的部分莫尔斯电码将变为 ['x','x','x..','x']。因此为了解码这个部分消息，我们将不得不用任何一个替换 x 。或 - 对于上述部分莫尔斯电码中每次出现的 x。在“x”未知的情况下，解码时 TEST 字的排列将是 ETST、EEDT、ETSE 等。我已经实现了莫尔斯部分解码功能，如下所示：

def morsePartialDecode(inputStringList):
    with open('words.txt','a') as wordfile:
        dictionaryFileLoc = './dictionary.txt'
        message_received = inputStringList
        message_received = ' '.join(inputStringList)
        for i in range(len(message_received)):
            x = 'x'
            y = '.'
        message = message_received.replace(x, y)
        message1 = message.split(",")
        message_converted = morseDecode(message1)
        print message_converted
        print >> wordfile, (message_converted)
        for i in range(len(message_received)):
            x = 'x'
            y = '-'
        message = message_received.replace(x, y)
        message2 = message.split(",")
        message_converted = morseDecode(message2)
        print >> wordfile, (message_converted)
        elements = []
    wordfile.closed
    return message_converted

def partialMorseCodeTest():
    test = ['x', 'x', 'x..', 'x']
    print morsePartialDecode(test)  

partialMorseCodeTest()

Output:
EESE
TTDT

我需要 ['x','x','x..','x'] 的所有组合，其中 x 替换为 .或 -。我的 morseDecode() 会将每个组合转换为各自的单词，如 EESE、TTDT 等morsedecode) 怎么办。提前致谢！

Answer 1

itertools 的绝佳案例

使用itertools.product的示例：

from itertools import product

def replace_x_with_all_combinations(morse):
    # only works with 1 and 1 only 'x' in each element
    all_perm = list()
    for v in morse:
        if 'x' in v:
            # create a list of permutations per element of the morse list
            # and append them to the all_perm list
            all_perm.append([v.replace('x','.'), v.replace('x','-')])
        else:
            # if no x found, then append the original element
            all_perm.append([v])
    # all_perm = [['.', '-'], ['.', '-'], ['...', '-..'], ['.', '-']]
    # the list all_perm needs to be unpacked before passing
    # to the product() generator, hence the *
    return list(product(*all_perm))

partial = ['x','x','x..','x']
result = replace_x_with_all_combinations(partial)
for e in result:
    print(e)

输出：

('.', '.', '...', '.')
('.', '.', '...', '-')
('.', '.', '-..', '.')
('.', '.', '-..', '-')
('.', '-', '...', '.')
('.', '-', '...', '-')
('.', '-', '-..', '.')
('.', '-', '-..', '-')
('-', '.', '...', '.')
('-', '.', '...', '-')
('-', '.', '-..', '.')
('-', '.', '-..', '-')
('-', '-', '...', '.')
('-', '-', '...', '-')
('-', '-', '-..', '.')
('-', '-', '-..', '-')

[编辑] 虽然我自己在上面的代码中设置了限制，但“仅适用于莫尔斯字符中的 1 个 x”让我感到困扰，所以下面的示例将在莫尔斯字符中丢失一个以上的数字，多个 'x'

from itertools import product


def replace_x_in_morse_charcter(morse_character):
    all_perm = [['.','-'] if c == 'x' else [c] for c in morse_character]
    p = list(product(*all_perm))
    return [''.join([v for v in e]) for e in p]


def replace_x_in_morse_word(morse):
    all_perm = [replace_x_in_morse_charcter(c) for c in morse]
    return list(product(*all_perm))


partial = ['x','x','x..','xx']
result = replace_x_in_morse_word(partial)
for e in result:
    print(e)

[编辑] 一个班轮的乐趣：

morse_word = ['x','x','x..','xx']
result = list(product(*[[''.join([v for v in e]) for e in list(product(*[['.','-'] if c == 'x' else [c] for c in cm]))] for cm in morse_word]))