在字典中查找特定的键值对

Question

my_dict = {1: ['Serena', 'Williams', 38],2: ['Bradley', 'Cooper', 45],3: ['Wendy', 'Williams', 56],4: ['Bill', 'Gates', 72], 5: ['Normani', 'Kordei', 24]}

I have that dictionary with a list as values and I'm trying to access say the age (index 2 in the list) of key 3 when found. I tried this code

def record(num):
    my_dict = {1: ['Serena', 'Williams', 38],2: ['Bradley', 'Cooper', 45],3: ['Wendy', 'Williams', 56],
               4: ['Bill', 'Gates', 72], 5:['Normani', 'Kordei', 24]}
    for k, v in my_dict.items():
        fname = v[0]
        lname = v[1]
        age = v[2]
        if my_dict.get(num) is None:
            print('Not found')
        else:
            print(num, age, 'Found')

record(3) # Call function

I want something like if I call the function with record(3) I just get the age corresponding to that key like this:

3 56 Found

Currently I get:

3 38 Found
3 45 Found
3 56 Found
3 72 Found
3 24 Found

Answer 1

You don't need to use a loop, you can just index directly into the dictionary.

def record(num):
    my_dict = {1: ['Serena', 'Williams', 38],2: ['Bradley', 'Cooper', 45],3: ['Wendy', 'Williams', 56],
               4: ['Bill', 'Gates', 72], 5:['Normani', 'Kordei', 24]}
    if num in my_dict:
        print(num, my_dict[num][2], "Found")
    else:
        print("Not found")

or use try-except to handle the "not found" case (which some may argue is more "Pythonic"):

def record(num):
    my_dict = {1: ['Serena', 'Williams', 38],2: ['Bradley', 'Cooper', 45],3: ['Wendy', 'Williams', 56],
               4: ['Bill', 'Gates', 72], 5:['Normani', 'Kordei', 24]}
    try:
        print(num, my_dict[num][2], "Found")
    except KeyError:
        print("Not found")

Answer 2

As noted in SuperStormer's answer , you should be directly accessing the record for num by invoking the key on the directory. However using the iteration process you do, the correct item to check is whether k matches the desired key num .

Note this approach is not recommended - this is just a clean-up of your method:

my_dict = {1: ['Serena', 'Williams', 38], 2: ['Bradley', 'Cooper', 45],
        3: ['Wendy', 'Williams', 56], 4: ['Bill', 'Gates', 72], 
        5:['Normani', 'Kordei', 24]}

def record(num):
    for k, v in my_dict.items():
        fname, lname, age = v
        if k == num:
            print(num, age, 'Found')
            return
    print (num, "Not found")  

for a in range(7):  # Call function repeatedly to check cases
    record(a)

The output from the seven calls to record above is:

0 Not found
1 38 Found
2 45 Found
3 56 Found
4 72 Found
5 24 Found
6 Not found