如何在 python 的字典中完成數學和變量賦值？

Question

Player1 = {
    "name":"Bob",
    "attack":7,
    "defence":5,
    "total":Player1["attack"]+Player1["defence"],
}

如何將字典中的總數設置為攻擊+防御？

Answer 1

不幸的是，據我所知，您要問的問題是……您最好使用 class

像這樣：

class Player:

    def __init__(self):
        self.name = "Bob"
        self.attack = 7
        self.defence = 5
        self.total = self.attack + self.defence

player = Player()
print(player.total)

您必須記住的是，您在聲明 dict 時並未對其進行實例化，因此在{}內您不能調用Player1 ，因為它在上下文中尚不存在。

通過使用類，您還可以通過執行以下操作來重用上面的示例：

class Player:

    def __init__(self, name, attack, defence):
        self.name = name
        self.attack = attack
        self.defence = defence
        self.total = self.attack + self.defence

player1 = Player(name="bob", attack=7, defence=5)
player2 = Player(name="bill", attack=10, defence=7)
print(player1.total)
print(player2.total)

編輯：修正錯字

Answer 2

您當前正在嘗試在創建Player1之前訪問它。

你可以這樣做：

Player1 = {
    "name":"Bob",
    "attack":7,
    "defence":5
}
Player1["total"] = Player1["attack"] + Player1["defence"]

但是，這並不理想，因為您需要記住在'attack'或'defence'發生變化時調整'total'字段。 最好即時計算總值，因為它不是昂貴的計算。

這可以通過編寫具有屬性total的Player class 來實現。

class Player:
    def __init__(self, name, attack, defence):
        self.name = name
        self.attack = attack
        self.defence = defence

    @property
    def total(self):
        return self.attack + self.defence

演示：

>>> Player1 = Player('Bob', 1, 2)
>>> Player1.name, Player1.attack, Player1.defence, Player1.total
('Bob', 1, 2, 3)

Answer 3

假設您不想自己計算鍵總計的值。 您可以將其初始化為None （標准做法。比省略它更好）。

Player1 = {
    "name":"Bob",
    "attack":7,
    "defence":5,
    "total":None
}

然后稍后更新它的值。

Player1["total"] = Player1["attack"] + Player1["defence"]