Function 只打印字典的最后 2 个键：值对

Question

I'm creating a function that takes a dictionary as a parameter. The dictionary is made up of a key which is a last name and a value is a list of first names.

The function should return a new dictionary where each key is the first letter of the key in the parameter, and the value is the number of items in the value of the parameter

Example

names = {"Stark": ["Ned", "Robb", "Sansa"], "Snow" : ["Jon"], "Lannister": ["Jaime", "Cersei", "Tywin"]}

{"S" : 3, "S" : 1,  "L": 3}

The function I've written is only printing '{'S': 1, 'L': 3}' the last 2 key, value pairs in the dictionary but I want {'S': 3, 'S': 1, 'L': 3} printed

def count_first_letter(names):
     beginning = []
     last = []
     for element, number in names.items():
       amount = len(number)
       first = element[0]
       last.append(amount)
       beginning.append(first)
    
     new = {key:value for key, value in zip(beginning, last)}
    
    
     return new
    
    
    
    print(count_first_letter({"Stark": ["Ned", "Robb", "Sansa"], "Snow": ["Jon"], "Lannister": ["Jaime", "Cersei", "Tywin"]}))

'{'S': 1, 'L': 3}'

Answer 1

Because 2 of your last names start with same letter: Stark, Snow. Thus, overwriting each other as dictionary keys are unique.

Answer 2

Your dictionary keys are getting overridden, so 'S': 3 is getting overridden by 'S': 1 because a dictionary cannot contain duplicate keys

To fix your problem, you would need to put them in a list like this:

new = [(key,value) for key, value in zip(beginning, last)]

output:

[('S', 3), ('S', 1), ('L', 3)]