如何將元組列表中的兩個元素分組爲字典？

Question

我想總結水果和顏色。有水果的元組及其相應顏色的名單，我希望計算的黃色的水果，然後構造一個詞典：

yellowfruit= { 'banana': 1, 'grape' : 2, 'orange': 2, 'peach': '4', 'pear':1 } 

以下是水果的信息

fruit= [ 
       ('apple', 'green'), 
       ('apple', 'red'), 
       ('banana', 'yellow'), 
       ('grape', 'green'), 
       ('grape', 'yellow'), 
       ('grape', 'yellow'), 
       ('grape', 'red'), 
       ('orange', 'yellow'), 
       ('orange', 'yellow'), 
       ('mango', 'green'), 
       ('peach', 'yellow'), 
       ('peach', 'red'), 
       ('peach', 'yellow'), 
       ('peach', 'yellow'), 
       ('peach', 'red'), 
       ('peach', 'yellow'), 
       ('peach', 'red'), 
       ('pear', 'yellow'), 
      ] 

這些是我的意見代碼：

fruit= [ 
     ('apple', 'green'), 
     ('apple', 'red'), 
     ('banana', 'yellow'), 
     ('grape', 'green'), 
     ('grape', 'yellow'), 
     ('grape', 'yellow'), 
     ('grape', 'red'), 
     ('orange', 'yellow'), 
     ('orange', 'yellow'), 
     ('mango', 'green'), 
     ('peach', 'yellow'), 
     ('peach', 'red'), 
     ('peach', 'yellow'), 
     ('peach', 'yellow'), 
     ('peach', 'red'), 
     ('peach', 'yellow'), 
     ('peach', 'red'), 
     ('pear', 'yellow'), 
    ] 

yellowfruit = { } # create an empty dictionary 
fruitname = fruit[0][0] # 'apple' is the first fruit 
for i in range(len(fruit)): # loop over the tuples in the fruit list 

    if fruit[i][0] == fruitname: 
     if fruit[i][1] == 'yellow': 
     # for the same kind of fruit, if its colour is yellow, count update for 1 
      n += 1 
     else: # if the same kind of fruit but not the colour of yellow 
      continue 

    else: 
     n = 1 # if not the same kind of fruit, refill the count as 1 
     fruitname = fruit[i][0] # if the fruit change, always update the current item as the fruit name 
    yellowfruit[fruitname] = n # create the dictionary 

print(yellowfruit) 

結果：

{'peach': 4, 'banana': 1, 'orange': 2, 'grape': 3, 'pear': 1, 'mango': 1} 

問題是什麼？

Answer 1

你依靠的是按水果排序的元組，但事實並非總是如此。爲了處理水果在詞典yellow_fruit中存在或不存在的兩種情況，我們使用yellow_fruit.get(fruit, 0)，其或者返回yellow_fruit[fruit]（如果fruit存在於yellow_fruit中）或0（如果它不存在）。請注意，字典是無序的，所以如果您重新運行程序，打印的鍵/值對可以自行排列。

tuple_list = [ 
    ('apple', 'green'), 
    ('apple', 'red'), 
    ('banana', 'yellow'), 
    ('grape', 'green'), 
    ('grape', 'yellow'), 
    ('grape', 'yellow'), 
    ('grape', 'red'), 
    ('orange', 'yellow'), 
    ('orange', 'yellow'), 
    ('mango', 'green'), 
    ('peach', 'yellow'), 
    ('peach', 'red'), 
    ('peach', 'yellow'), 
    ('peach', 'yellow'), 
    ('peach', 'red'), 
    ('peach', 'yellow'), 
    ('peach', 'red'), 
    ('pear', 'yellow'), 
] 

yellow_fruit = {} 
for fruit, colour in tuple_list: 
    if colour == 'yellow': 
     yellow_fruit[fruit] = yellow_fruit.get(fruit, 0) + 1 
print(yellow_fruit) # {'banana': 1, 'orange': 2, 'grape': 2, 'peach': 4, 'pear': 1}