如何从两个字符串列表的笛卡尔积创建列表

Question

我有两个如下所示的字符串列表：

print(objects_list)
print(verb_list)

他们输出：

['parking_meter', 'sink', 'teddy_bear']
 
 ['sail', 'fill', 'fly', 'greet', 'hit', 'hose', 'hunt', 'install',
 'kick', 'launch', 'move', 'pick', 'repair', 'sit_at', 'squeeze',
 'stab', 'straddle', 'talk_on']

我希望这两个列表的产品格式如下：

[['parking_meter','sail'],['parking_meter','fill'],['parking_meter','fly']......]

我试过这段代码

list3 = [[str(l),str(n)] for l in objects_list for n in verb_list]
print(list3)

但它输出：

[['[', '['], ['[', "'"], ['[', 's'], ['[', 'a'], ['[', 'i'], ['[',
 'l'], ['[', "'"], ['[', ','], ['[', ' '], ['[', "'"], ['[', 'f'],
 ['[', 'i'], ['[', 'l'], ['[', 'l'], ['[', "'"], ['[', ','], ['[', '
 '], ['[', "'"], ['[', 'f'], ['[', 'l'], ['[', 'y'], [.....

有什么办法吗？

Answer 1

您的代码应该可以正常工作。我怀疑您的实际代码中还有其他一些不必要的 str() 函数调用：

objects_list = ['parking_meter', 'sink', 'teddy_bear']
verb_list = ['sail', 'fill', 'fly', 'greet', 'hit', 'hose',
             'hunt', 'install', 'kick', 'launch', 'move', 
             'pick', 'repair', 'sit_at', 'squeeze', 'stab', 
             'straddle', 'talk_on']

list3 = [[o,v] for o in objects_list for v in verb_list]

[['parking_meter', 'sail'], ['parking_meter', 'fill'], ['parking_meter', 'fly'], ['parking_meter', 'greet'], ['parking_meter', 'hit'], ['parking_meter', 'hose'], ['parking_meter', 'hunt'], ['parking_meter', 'install'], ['parking_meter', 'kick'], ['parking_meter', 'launch'], ['parking_meter', 'move'], ['parking_meter', 'pick'], ['parking_meter', 'repair'], ['parking_meter', 'sit_at'], ['parking_meter', 'squeeze'], ['parking_meter', 'stab'], ['parking_meter', 'straddle'], ['parking_meter', 'talk_on'], ['sink', 'sail'], ['sink', 'fill'], ['sink', 'fly'], ['sink', 'greet'], ['sink', 'hit'], ['sink', 'hose'], ['sink', 'hunt'], ['sink', 'install'], ['sink', 'kick'], ['sink', 'launch'], ['sink', 'move'], ['sink', 'pick'], ['sink', 'repair'], ['sink', 'sit_at'], ['sink', 'squeeze'], ['sink', 'stab'], ['sink', 'straddle'], ['sink', 'talk_on'], ['teddy_bear', 'sail'], ['teddy_bear', 'fill'], ['teddy_bear', 'fly'], ['teddy_bear', 'greet'], ['teddy_bear', 'hit'], ['teddy_bear', 'hose'], ['teddy_bear', 'hunt'], ['teddy_bear', 'install'], ['teddy_bear', 'kick'], ['teddy_bear', 'launch'], ['teddy_bear', 'move'], ['teddy_bear', 'pick'], ['teddy_bear', 'repair'], ['teddy_bear', 'sit_at'], ['teddy_bear', 'squeeze'], ['teddy_bear', 'stab'], ['teddy_bear', 'straddle'], ['teddy_bear', 'talk_on']]

Answer 2

试试这个，使用 itertools 库。有一个叫做 product 的函数可以得到一个笛卡尔积。

import itertools

x = ['parking_meter', 'sink', 'teddy_bear']

y = ['sail', 'fill', 'fly', 'greet', 'hit', 'hose', 'hunt', 'install', 'kick', 'launch', 'move', 'pick', 'repair', 'sit_at', 'squeeze', 'stab', 'straddle', 'talk_on']

然后你可以做这个 2-liner，（因为 product 函数返回一个元组但你需要一个列表）

z = list(itertools.product(x,y))
z = [list(z) for z in z]

或者这个 1-liner，

z = [list(tup) for tup in list(itertools.product(x, y))]

然后我，

print (z)

这给了我

[['parking_meter', 'sail'],
 ['parking_meter', 'fill'],
 ['parking_meter', 'fly'],
 ['parking_meter', 'greet'],
 ['parking_meter', 'hit'],
 ['parking_meter', 'hose'],
 ['parking_meter', 'hunt'],
 ['parking_meter', 'install'],
 ['parking_meter', 'kick'],
 ['parking_meter', 'launch'],
 ['parking_meter', 'move'],
 ['parking_meter', 'pick'],
 ['parking_meter', 'repair'],
 ['parking_meter', 'sit_at'],
 ['parking_meter', 'squeeze'],
 ['parking_meter', 'stab'],
 ['parking_meter', 'straddle'],
 ['parking_meter', 'talk_on'],
 ['sink', 'sail'],
 ['sink', 'fill'],
 ['sink', 'fly'],......

Answer 3

从您得到的输出来看，您的输入列表似乎是字符串，而不是列表。

好像objects_list 是print(objects_list) 的输出，而不是列表本身。

因此，当迭代objects_list 时，不是迭代列表项，而是迭代其字符串表示的字符：

"["
"'"
"p"
"a"
...

您的代码在其他方面是正确的，除了您不需要在列表推导中将元素转换为字符串。

list3 = [[l, n] for l in objects_list for n in verb_list]

Answer 4

您的代码运行良好，并给了我预期的输出。我不确定是否还有其他问题。可能是您的列表没有像我一样声明...如果您是从其他来源创建此列表...您应该检查格式。

注意：我已在 Python 3.9.5 上运行此代码

objects_list = ['parking_meter', 'sink', 'teddy_bear']
verb_list = ['sail', 'fill', 'fly', 'greet', 'hit', 'hose', 'hunt', 'install', 'kick', 'launch', 'move', 'pick', 'repair', 'sit_at', 'squeeze', 'stab', 'straddle', 'talk_on'] 

list3 = [[str(l),str(n)] for l in objects_list for n in verb_list] 
print(list3)

Output:
[['parking_meter', 'sail'], ['parking_meter', 'fill'], ['parking_meter', 'fly']['parking_meter', 'greet'], ['parking_meter', 'hit'], ['parking_meter', 'hose'], ['parking_meter', 'hunt'], ['parking_meter', 'install'], ['parking_meter', 'kick'], ['parking_meter', 'launch'], ['parking_meter', 'move'], ['parking_meter', 'pick'], ['parking_meter', 'repair'], ['parking_meter', 'sit_at'], ['parking_meter', 'squeeze'], ['parking_meter', 'stab'], ['parking_meter', 'straddle'], ['parking_meter', 'talk_on'], ['sink', 'sail'], ['sink', 'fill'], ['sink', 'fly'], ['sink', 'greet'], ['sink', 'hit'], ['sink', 'hose'], ['sink', 'hunt'], ['sink', 'install'], ['sink', 'kick'], ['sink', 'launch'], ['sink', 'move'], ['sink', 'pick'], ['sink', 'repair'], ['sink', 'sit_at'], ['sink', 'squeeze'], ['sink', 'stab'], ['sink', 'straddle'], ['sink', 'talk_on'], ['teddy_bear', 'sail'], ['teddy_bear', 'fill'], ['teddy_bear', 'fly'], ['teddy_bear', 'greet'], ['teddy_bear', 'hit'], ['teddy_bear', 'hose'], ['teddy_bear', 'hunt'], ['teddy_bear', 'install'], ['teddy_bear', 'kick'], ['teddy_bear', 'launch'], ['teddy_bear', 'move'], ['teddy_bear', 'pick'], ['teddy_bear', 'repair'], ['teddy_bear', 'sit_at'], ['teddy_bear', 'squeeze'], ['teddy_bear', 'stab'], ['teddy_bear', 'straddle'], ['teddy_bear', 'talk_on']]