需要幫助理解python中的字典

-1

我是新來編碼並寫了一個腳本。我不明白爲什麼顯示的總數是錯誤的，每次運行程序時都會改變。我知道字典不會每次都按相同的順序存儲關鍵字和值，但我不明白爲什麼總數是錯誤的並且從不相同？有人可以幫忙嗎？我正在尋找一個解釋，以便從我的錯誤中學習。需要幫助理解python中的字典

stock = [["mp40", 4], ["crowbar", 3], ["machete", 4], ["5_person_tent", 3], 
     ["gps", 10], ["duffle_bag", 3], ["first_aid_kit", 2], ["horse", 1], 
     ["military_mre", 7], ["camping_stove", 1], ["hunting_vest", 2], 
     ["jogging_pants", 3], ["timberlands", 2], ["gas_generator", 3], 
     ["gasoline", 500], ["gas_can", 100], ["pontiac_grand_dam", 1]] 

prices = [["mp40", 390], ["crowbar", 20], ["machete",40],["5_person_tent",250], 
      ["gps", 97], ["duffle_bag",20], ["first_aid_kit",15], ["horse", 3000], 
      ["military_mre",15],["camping_stove",15], ["hunting_vest", 60], 
      ["jogging_pants", 60], ["timberlands", 150], ["gas_generator",180], 
      ["gasoline", 3],["gas_can", 20], ["pontiac_grand_dam", 2000]] 


def buy(): 
    purchase =input("What item you want to buy?\n") 
    total = 0 
    for item in stock: 
     if purchase in stock.keys(): 
      if stock[item] > 0: 
       amount =int(input("How many would you like to purchase?\n")) 
       total += (prices[item]*(amount)) 
       stock[item] -=(amount) 
       print ('You owe'+' '+'$'+str(total)) 
       input('press enter to continue \n') 
       return total 

      if stock[item]<1: 
       print ("we don't have any left\n") 

     if purchase!=item: 
      print ("We do not sell that.\n") 

a=0 
while a==0: 
    buy()

來源

2016-04-21 Squirrel Lord

你沒有字典這裏。你有清單的列表。 – Andy

對於初學者，此代碼不會運行。 'stock'是一個列表，而不是一本字典。 – chepner

字典由'{'和'}'分隔，'['和']'表示列表 – PurityLake

你需要讓stock和prices字典，而不是名單。幸運的是，您當前的數據使這變得簡單，因爲dict可以將鍵值對列表作爲參數。也就是說，

stock = [...] # current definition 
stock = dict(stock) 

prices = [ ... ] # current definition 
prices = dict(prices)

定義詞典「手動」看起來像

stock = {"mp40":4, 
     "crowbar":3, 
     "machete":4, } # etc

來源

2016-04-21 14:33:42 chepner

非常感謝！ –

需要幫助理解python中的字典

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