战舰:如何自动创建实例？

Question

我在做一个战舰游戏。我创建了一个Ship类来给船一个位置。

在创建类之后，我必须创建所有的实例，我想知道是否有一种方法可以自动化。

程序的大部分都是无关紧要的，但我把它留在这里，以防它可能会影响它是否可以自动化。

import random

class Ship(object):

    def __init__(self, length):
        self.length = length

    def direction(self):
        vh = random.choice(['v','h'])
        return vh

    def location(self):
        space = []
        row = random.randint(0, 10-self.length)
        column = random.randint(0, 10-self.length)
        if self.direction == 'v':
            for x in range(self.length):
                space.append(f'{column}{row+x}')
        else:
            for x in range(self.length):
                space.append(f'{column}{row+x}')
        return space

ships_amount = {
    'carrier' : 1,
    'battleship' : 2,
    'cruiser' : 3,
    'destroyer' : 4
}

ships_length = {
    'carrier' : 5,
    'battleship' : 4,
    'cruiser' : 3,
    'destroyer' : 2
}

我想这样做：

carrier1 = Ship(ships_length['carrier'])
battleship1 = Ship(ships_length['battleship'])
battleship2 = Ship(ships_length['battleship'])
cruiser1 = Ship(ships_length['cruiser'])
cruiser2 = Ship(ships_length['cruiser'])
cruiser3 = Ship(ships_length['cruiser'])
destroyer1 = Ship(ships_length['destroyer'])
destroyer2 = Ship(ships_length['destroyer'])
destroyer3 = Ship(ships_length['destroyer'])
destroyer4 = Ship(ships_length['destroyer'])

但却是自动的

Answer 1

你可以遍历你想要的船并查找它们的长度来制作它们：

 ships = []
 for type_of_ship in ships_amount:
   ships.append(Ship(ships_length[type_of_ship]))

甚至是

ships = [Ship(ships_length[k]) for k in ships_amount]

(在第二个示例中，ky是key的简写，或者现在在for循环中称为type_of_ship )

这将为您提供每种类型的一艘船。

这不会给你提供名为'carrier1‘等的变量，但你将能够对ships中的每一项做一些事情。

例如：

for ship in ships:
    print(ship.length)

为了得到规定的数量，或者每种类型的船的数量，你需要在循环中制造额外的船。通过在items()上迭代，您可以得到一个键和值，我称之为k和v，但应该有更好的名称。字典中的值告诉您有多少：

ships = []
for k, v in ships_amount.items():
    ships.extend([Ship(ships_length[k]) for _ in range(v)])

这给你提供了你想要的10艘船。

Answer 2

如果您为所需的每个船舶模型创建了Ship的子类，则可以将它们分组到Fleet中，然后在一行代码中直接创建舰队……

可能是这样的：

import random

class Ship:             # this becomes an abstract class, not to be instanciated
                        # you could have it inherit from ABC (Abstract Base Class)
    def __init__(self):
        self.length = self.__class__.length
        self.heading = None
        self.set_heading()

        self.location = None
        self.set_location()

    def set_heading(self):
        self.heading = random.choice(['v','h'])

    def set_location(self):   # this method needs more work to prevent
                              # ships to occupy the same spot and overlap 
        space = []
        row = random.randint(0, 10 - self.length)
        column = random.randint(0, 10 - self.length)
        if self.heading == 'v':
            for c in range(self.length):
                space.append((row, column + c))
        elif self.heading == 'h':
            for r in range(self.length):
                space.append((row + r, column))
        self.location = space

    def __str__(self):
        return f'{self.__class__.__name__} at {self.location}'


class AircraftCarrier(Ship):    # every type of ship inherits from the base class Ship
    length = 5                  # Each class of ship can have its own specifications
                                # here, length, but it could be firepower, number of sailors, cannons, etc...

class BattleShip(Ship):
    length = 4

class Cruiser(Ship):
    length = 3

class Destroyer(Ship):
    length = 2


class Fleet:
    ships_number = {AircraftCarrier : 1,
                    BattleShip: 2, 
                    Cruiser: 3, 
                    Destroyer: 4}
    def __init__(self):
        self.ships = [ship() for ship, number in Fleet.ships_number.items() 
                      for _ in range(number)]

    def __str__(self):
        return '\n'.join([str(ship) for ship in self.ships])


if __name__ == '__main__':

    fleet = Fleet()         # <-- the creation of the entire Fleet of Ships 
    print(fleet)            #     takes now one line of code now

输出示例：

(位置是随机分配的，每次运行都会有所不同。)

AircraftCarrier at [(1, 2), (2, 2), (3, 2), (4, 2), (5, 2)]
BattleShip at [(5, 3), (6, 3), (7, 3), (8, 3)]
BattleShip at [(5, 1), (6, 1), (7, 1), (8, 1)]
Cruiser at [(4, 7), (5, 7), (6, 7)]
Cruiser at [(0, 5), (0, 6), (0, 7)]
Cruiser at [(6, 6), (7, 6), (8, 6)]
Destroyer at [(4, 8), (5, 8)]
Destroyer at [(3, 5), (4, 5)]
Destroyer at [(1, 5), (1, 6)]
Destroyer at [(2, 1), (2, 2)]

添加新的船舶类型：

添加新的船舶类型非常简单:只需创建一个继承自抽象基类Ship的新类，并将新船舶的数量添加到舰队组合中就足够了：

class Submarine(Ship):
    length = 1

Fleet.ships_number[Submarine] = 5   # or add this entry directly in the class Fleet data

舰队现在有额外的5艘潜艇：

AircraftCarrier at [(4, 1), (5, 1), (6, 1), (7, 1), (8, 1)]
BattleShip at [(5, 5), (6, 5), (7, 5), (8, 5)]
BattleShip at [(0, 0), (1, 0), (2, 0), (3, 0)]
Cruiser at [(5, 2), (5, 3), (5, 4)]
Cruiser at [(2, 0), (3, 0), (4, 0)]
Cruiser at [(7, 7), (8, 7), (9, 7)]
Destroyer at [(4, 3), (5, 3)]
Destroyer at [(2, 1), (2, 2)]
Destroyer at [(0, 8), (1, 8)]
Destroyer at [(3, 6), (3, 7)]
Submarine at [(8, 8)]
Submarine at [(0, 7)]
Submarine at [(3, 4)]
Submarine at [(5, 9)]
Submarine at [(9, 3)]