多次迭代三个列表，在每次迭代中依次从列表中选取一个元素

Question

我想遍历三个列表中的每一个，在每次迭代中依次从每个列表中选取一个元素。

subjects=["Americans","Indians"]
verbs=["plays","watch"]
objects=["Baseball","cricket"]
for i,j,k in zip(subjects,verbs,objects):
    print(i,j,k)

以上代码输出如下：

Americans plays Baseball

Indians watch cricket

但预期的输出是：

Americans play Baseball.

Americans play Cricket.

Americans watch Baseball.

Americans watch Cricket.

Indians play Baseball.

Indians play Cricket.

Indians watch Baseball.

Indians watch Cricket.

Answer 1

您可以这样迭代解决方案：

subjects=["Americans","Indians"] 
verbs=["plays","watch"] 
objects=["Baseball","cricket"]


for s in subjects:
    for v in verbs:
        for o in objects:
            print(s,v,o+".")

Answer 2

使用itertools.product得到所有可能的组合然后打印出来

>>> subjects=["Americans","Indians"]
>>> verbs=["plays","watch"]
>>> objects=["Baseball","cricket"]
>>> 
>>> from itertools import product
>>> for x in product(subjects,verbs,objects):
...     print('{} {} {}'.format(*x))
... 
Americans plays Baseball
Americans plays cricket
Americans watch Baseball
Americans watch cricket
Indians plays Baseball
Indians plays cricket
Indians watch Baseball
Indians watch cricket

Answer 3

itertools.product 是最好的解决方案，但如果您不想导入模块，下一个最有效的解决方案是生成器表达式。

subjects = ["Americans", "Indians"]
verbs = ["play", "watch"]
objects = ["Baseball", "Cricket"]

# paragraph = "\n".join(f"{s} {v} {o}." for s in subjects for v in verbs for o in objects)  # Alternative single-liner
for sentence in (f"{s} {v} {o}." for s in subjects for v in verbs for o in objects):
    print(sentence)

输出

Americans play Baseball.
Americans play Cricket.
Americans watch Baseball.
Americans watch Cricket.
Indians play Baseball.
Indians play Cricket.
Indians watch Baseball.
Indians watch Cricket.

多次迭代三个列表，在每次迭代中依次从列表中选取一个元素

Iterate through three lists multiple times sequentially picking one element from a list in each iteration

python

for-loop

iterator

nested-loops

string-interning