Python-如何根据嵌套字典中的值返回字典键？

Question

I have a dictionary of dictionaries in Python.

I would like a way to go through each dict of dict, check the value of the 'val' key in each dictionary then return the initial dictionary key where 'val' == 0.

dict = {
    1: {'x': 'a', 'val': 1},
    2: {'x': 'b', 'val': 1},
    3: {'x': 'c', 'val': 0},
    4: {'x': 'c', 'val': 0}
}

I tried the following but that just return 3 and 4.

for itemid, iteminfo in data.items():
    for key in iteminfo:
        if iteminfo[key] == 0:
            print(str(itemid))

In the example above I would like 3 returned as it's the first instance where 'val' == 0.

Answer 1

If you just want the first occurrence of 'val' being paired with 0 (without any specific order, since dicts in python aren't ordered), you could use a break with the conditional statement inside your loop:

mydict = {
    1: {'x': 'a', 'val': 1},
    2: {'x': 'b', 'val': 1},
    3: {'x': 'c', 'val': 0},
    4: {'x': 'c', 'val': 0}
}

for key, value in mydict.items():
    if value['val'] == 0:
        print(key)
        break

If the order is important, you can go with an ordered dict