Question

以下是该计划的代码： 我试图实现一个vector类，因为我在python中了解了运算符重载。我能够创建一个矢量类，它可以像列表一样使用像len（vector），vector1 + vector2（加法运算符重载）和减法这样的操作。但我发现了一个问题。这是程序的代码，我已经说明了下面的问题：

class vector:
"""Initialize Vector"""
def __init__(self,d):
    self.coords = [0]*d

def __len__(self):
    return len(self.coords)

def __getitem__(self, item): #Getting an item from a vector
    return self.coords[item]

def __setitem__(self, key, value):
    self.coords[key] = value

def __add__(self, other):
    if(len(self)!= len(other)):
        print("Don't add these too ! they are not same types :P")
    else:
        result = vector(len(self))
        for i in range(0,len(result)):
            result[i] = self[i] + other[i]
        return result
def __sub__(self, other):
    if(len(self) != len(other)):
        print("Dont subtract these two!")
    else:
        result = vector(len(self))
        for i in range(0,len(result)):
            result[i] = self[i] - other[i]
        return result

def __eq__(self, other):
    return self.coords == other.coords

def __ne__(self, other):
    return self.coords != other.coords

def __str__(self):
    return '<'+ str(self.coords)[1:-1] +'>'

print("Input for vector 1")
x = vector(2)
for i in range(0,len(x)):
    x[i] = int(input('Enter a number\n'))
print("Input for vector 2")
y = vector(2)
for i in range(0,len(y)):
    y[i] = int(input('Enter a number\n'))

z = x-y
print(str(x))
print("  +  ")
print(str(y))
print("  =  ")
print(str(z))

如果我添加一个矢量+列表但列表+矢量给出错误，它会起作用。我该如何实现另一个。

Answer 1

您想要实施__radd__。由于它应该与此处__add__执行相同的操作，因此您只需为其分配__add__：

class vector:
  ...
  def __add__(self, other):
    if(len(self)!= len(other)):
      print("Don't add these too ! they are not same types :P")
    else:
      result = vector(len(self))
      for i in range(0,len(result)):
        result[i] = self[i] + other[i]
      return result

  __radd__ = __add__
  ...

如何实现形式[1,2,3,4] + v的向量加法，其中v是向量，[1,2,3,4]是python中的列表？

1 个答案: