Question

Okey，所以我正在学习python，我试图创建这个基本的挑选销售游戏......

import random
global gold
gold = 0

class Fruit:
    def __str__(self):
        return self.name

    def __repr__(self):
        return self.name

class Apple(Fruit):
    def __init__(self):
        self.name = "Apple"
        self.desc = "An Red Apple!"
        self.value = "2 Gold"

class Grapes(Fruit):
    def __init__(self):
        self.name = "Grapes"
        self.desc = "Big Green Grapes!"
        self.value = "4 Gold"

class Banana(Fruit):
    def __init__(self):
        self.name = "Banana"
        self.desc = "Long, Fat Yellow Bananas"
        self.value = "5 Gold"

class Orange(Fruit):
    def __init__(self):
        self.name = "Orange"
        self.desc = "Big Orange Orange"
        self.value = "7 Gold"


inventory = []

print ("Fruits!")
print ("To see your inventroy press: i")
print ("To sell fruits press: s")
print ("To pick fruits press: p")

def action():
    return input("Action: ")


def i ():
    print ("Your Inventory: ")
    print ("*" + str(inventory))

def p ():
    pick = [Apple(), Orange(), Grapes(), Banana()]
    inventory.append (random.choice(pick))

def s ():
    print ("...")

while True:
    actioninput = action()
    if actioninput in ["i", "İ"]:
        i ()
    elif actioninput in ["s", "S"]:
        s ()
    elif actioninput in ["p", "P"]:
        p ()
    else:
        print ("Invalid Action!")

所以我的问题是：

，我想打印已添加到列表中的项目。我试了一些东西，但他们没有工作......
我不知道怎么做＆＃34;出售＆＃34;功能，如何从列表中删除项目并将其值添加到全球黄金？

我编辑了def s（）：就像这样，我得到一个错误：

def s():
    global gold
    sell = input ("What item would you like to sell?")
    if sell == "Apple":
        inventory.remove (Apple)
        gold = gold + 2
    elif sell == "Orange":
        inventory.remove (Orange)
        gold = gold + 7
    elif sell == "Banana":
        inventory.remove (Banana)
        gold = gold + 4
    elif sell == "Grapes":
        inventory.remove (Grapes)
        gold = gold + 5

ValueError: list.remove(x): x not in list

Answer 1

＆＃34;在def p():中，我想打印已添加到列表中的项目。＆＃34;

最简单的方法是使用中间变量：

def p ():
    pick = [Apple(), Orange(), Grapes(), Banana()]
    fruit_picked = random.choice(pick)
    inventory.append (fruit_picked)
    print("you picked a", fruit_picked)

您还可以使用indice [-1]获取列表的最后一个元素：

def p ():
    pick = [Apple(), Orange(), Grapes(), Banana()]
    inventory.append (random.choice(pick))
    print("you picked a", inventory[-1])

＆＃34;如何从列表中删除项目并将其值添加到全球黄金？＆＃34;

使用list.pop弹出一个项目，然后使用.value属性执行操作：

def s():
    global gold #need this in the function that you are modifying the global value
    fruit_sold = inventory.pop() #pop the last item
    gold += fruit_sold.value

＆＃34;如何从列表中选择要删除的特定元素＆＃34;

为此，有几种方法，如果不对Fruit类进行修改，您可以遍历列表并检查与输入名称相同的水果：

def s():
    global gold
    fruit_to_sell = input("what kind of fruit do you want to sell? ")
    for fruit in inventory:
        if fruit.name == fruit_to_sell:
            gold+=fruit.value
            inventory.remove(fruit)
            print("ok, you just sold a(n) {0} for {0.value} gold".format(fruit))
            return #finish the function
    #if no fruit was found
    print("you don't have any of those kind of fruit \n" + 
          "(This demo doesn't check for capitalization)")

您收到错误的原因是您尝试从广告资源中删除<strong>类，列表中只有Fruit对象，因此不会产生大量的感：

Apple == Apple() #almost always false, unless you   specifically overloaded __eq__ to make it True.

你可以改变你的Fruit类，这样只要水果是相同的类型（子类），它们就会比较相等：

class Fruit:
    def __eq__(self,other):
        return type(self) == type(other) 
    ...

那么您的销售可能只是稍微调整以删除任何实例：

def s():
    global gold
    sell = input ("What item would you like to sell?")
    if sell == "Apple":
        inventory.remove (Apple()) #make an instance here@
        gold = gold + 2
    elif sell == "Orange":
        inventory.remove (Orange())
        ... #you get the point

虽然如果你试图卖苹果但没有，这仍然会引起错误，你可能会更好地检查一下是否有第一个：

def s():
    global gold
    sell = input ("What item would you like to sell?")
    if sell == "Apple":
        selling = Apple()
    elif sell == "Orange":
        selling = Orange()
    elif sell == "Banana":
        selling = Banana()
    elif sell == "Grapes":
        selling = Grapes()
    if selling in inventory: #make sure you have some of what ever you are selling before trying to sell it!
        inventory.remove(selling)
        gold += int(selling.value.rstrip(" Gold"))
         # I didn't realize value was a str, this shoddy conversion
         #  works but is not a very good solution
    else:
        print("you don't have any of those!\n"+
              "(This demo doesn't check for capitalization)")

Answer 2

使用isinstance（）来检测对象所属的类。

保持全局变量不是一个好方法。也许开始构建一个值来传递函数作为一个帐户。

然后在购买之前检查您的余额。（预算外）等

Answer 3

list_name[-1]是列表中的最后一项，因此是最近附加的项目。

在您的情况下：inventory[-1]

在sell函数中，您可以使用list_name.remove('element_to_be_removed')删除列表中的元素。

在你的情况下：

fruit_to_remove = inventory[-1]
inventory.remove(fruit_to_remove)

或使用list.pop()。（根据Tadhg McDonald-Jensen的评论）

打印最后一项添加到列表中

3 个答案: