有人可以解释为什么这有效吗？ (Python 迭代器)

Question

我有一本字典，里面有一些宠物的名字和它们相应的信息，还有一个主人名字的列表。该代码的目标是通过从列表（所有者）中提取名称并在字典中创建新键：值对来更新字典。

owners = ["adam", "sandra", "ashley"]
pets = {
"buster": {
    "type": "dog",
    "colour": "black and white",
    "disposition": "sassy",
},
"jojo": {
    "type": "cat",
    "colour": "grey",
    "disposition": "grumpy",
},
"amber": {"type": "cat", "colour": "black", "disposition": "playful"},

}

iterator = iter(pets.values())
for owner in owners:
    for pet_info in iterator:
        try:
            pet_info["owner"] = owner
            break
        except StopIteration:
            print("The end")
print(pets)



Output

{
'buster': {'type': 'dog', 'colour': 'black and white', 'disposition': 'sassy', 'owner': 'adam'}, 
'jojo': {'type': 'cat', 'colour': 'grey', 'disposition': 'grumpy', 'owner': 'sandra'}, 
'amber': {'type': 'cat', 'colour': 'black', 'disposition': 'playful', 'owner': 'ashley'}
}

使用 iter() 函数后，我能够生成我想要的输出。因此，我试图弄清楚 iter() 函数是如何使这成为可能的。（我做了 google 但搜索结果不是我要找的）

提前致谢！

Answer 1

你可以这样做，前提是 'pets' 中的键数与 'owners' 中的元素数相同：

owners = ["adam", "sandra", "ashley"]
pets = {
    "buster": {
        "type": "dog",
        "colour": "black and white",
        "disposition": "sassy",
    },
    "jojo": {
        "type": "cat",
        "colour": "grey",
        "disposition": "grumpy",
    },
    "amber": {
        "type": "cat",
        "colour": "black",
        "disposition": "playful"}}

for p, o in zip(pets.values(), owners):
    p['owner'] = o

print(pets)

Answer 2

pet.values() 是一个列表，而 iter(pet.values()) 给你一个 list_iterator。检查以下示例：

a=[1,2,3]
ia = iter(a)

for i in a:
    print(i)
    break

for i in a:
    print(i)
    break

for i in a:
    print(i)
    break

for i in ia:
    print(i)
    break


for i in ia:
    print(i)
    break

for i in ia:
    print(i)
    break

输出只是说明了你在使用 iter() 函数时可能忽略的情况。

有人可以解释为什么这有效吗？ (Python 迭代器)

Could someone please explain why this works? (Python Iterator)

python

iterator

nested-loops