覆盖__add __（self，other）对self和other具有相同的实例

Question

我正在尝试为我的类Matrix编写一个新的 add （） - 方法，我正在实现它而不使用numpy。

使用我的add方法时出现以下问题：

    @classmethod        
    def __add__(self, other):

    print(self._data)
    print(other.data)

    row = len(self._data)
    column = len(self._data[0])
    addition = [[0 for c in range(column)] for r in range(row)]

    for i in range(row):
        for j in range(column):
            addition[i][j] += self._data[i][j] + other[i][j]

    return Matrix(addition)

打印为self和其他产生相同的值，尽管它不应该：

a = Matrix([[1, 2], [3, 4]])
b = Matrix.filled(2, 2, 1)
c = a + b

打印输出，清楚地显示c = b + b：

[[1, 1], [1, 1]]
[[1, 1], [1, 1]]

这是我为我的课程实现的其余代码：

class Matrix(object):

#initializes instance of Matrix
@classmethod
def __init__(self, iterable):
    self._data = iterable

    count = len(iterable[0])
    for i in range(len(iterable)):
        for j in range(len(iterable[i])):
            assert count == len(iterable[i])        
            assert type(iterable[i][j]) == int or type(iterable[i][j]) == float


#get item at key - a[0,1] -> a[0][1] 
@classmethod
def __getitem__(self, key):
    if (isinstance(key,int)):
        return self._data[key]

    else:
        return self._data[key[0]][key[1]]

#set value at key - a[1,0] = 42 -> a[1][0] = 42
@classmethod
def __setitem__(self, key, value):
    if (isinstance(key,int)):
        self._data[key] = value
    else:
        self._data[key[0]][key[1]] = value    


@classmethod
def __str__(self):
    k = "["
    for i in self._data:

            k = k + str(i)
            k = k +"," + "\n" + " "

    return k[:-3] + "]"                       


#builds matrix with dimensions row * column    
@staticmethod
def filled(rows,cols, value):
    matrix = [[value] * cols for i in range(rows)]
    return Matrix(matrix)

#creates and returns copy of matrix
@property
def data(self):
    matrix = copy.deepcopy(self._data)
    return matrix

非常感谢你的时间和帮助