[Beginner] Code Challenge: Dictionaries 1

1. Sum Values

• sum up all the values in the dictionary

def sum_values(my_dictionary):
  value_sum = 0
  for value in my_dictionary.values():
    value_sum += value
  return value_sum

 

 

2. Even Keys

Next, we are going to do something similar, but we are going to use the keys in order to retrieve the values. Additionally, we are going to only look at every even key within the dictionary.

def sum_even_keys(my_dictionary):
  total = 0
  for key in my_dictionary.keys():
    if key % 2 == 0:
      total += my_dictionary.values(key)
  return total

오류

TypeError: values() takes no arguments (1 given)

수정

def sum_even_keys(my_dictionary):
  total = 0
  for key in my_dictionary.keys():
    if key % 2 == 0:
      total += my_dictionary[key]
  return total

 

 

3. Add Ten

modify the values within the dictionary, adding 10 to every value and returning modified dictionary

def add_ten(my_dictionary):
    for key in my_dictionary.keys():
        my_dictionary[key] = my_dictionary.values() + 10
    return my_dictionary

오류

TypeError: unsupported operand type(s) for +: 'dict_values' and 'int'

수정1

def add_ten(my_dictionary):
    for key in my_dictionary.keys():
        my_dictionary[key] = int(my_dictionary.values()) + 10
    return my_dictionary

오류

TypeError: int() argument must be a string, a bytes-like object or a real number, not 'dict_values'

수정 (해설지 참고)

def add_ten(my_dictionary):
    for key in my_dictionary.keys():
        my_dictionary[key] += 10
    return my_dictionary

dictionary.values() 결과값 종류 / dictionary[key] 결과값 종류 알아보기

 

 

4. Values That Are Keys

making a program that will create a family tree

using a dictionary, return a list of all the children who are parents of other children

(values that hold values!  - a nested dictionary(중첩 사전))

 

방법 1

def values_that_are_keys(my_dictionary):
  keyvalues = []
  for value in my_dictionary.values():
    if value in my_dictionary.keys():
      keyvalues.append(value)
  return keyvalues

 

방법 2.

def values_that_are_keys(my_dictionary):
  return [value for value in my_dictionary.values() if value in my_dictionary.keys()]

 

 

5. Largest Value

create a function that finds the maximum value in the dictionary and returns the associated key

def max_key(my_dictionary):
    max_value = 0
    for key in my_dictionary.keys():
        if my_dictionary[key] >= max_value:
            max_key = key
            max_value = my_dictionary[key]
    return max_key

 

다른 방법 (정답지)

def max_key(my_dictionary):
  largest_key = float("-inf")
  largest_value = float("-inf")
  for key, value in my_dictionary.items():
    if value > largest_value:
      largest_value = value
      largest_key = key
  return largest_key

We start by using float("-inf") in order to initialize them to the lowest possible value. To retrieve the key and value at the same time, we use the items() function.

 

차이점 비교해보기