在类的实例中，可以使用一个方法返回的值作为调用另一个方法的参数吗

Question

class A:
   def __init__(self, matrix=[]):
       self.matrix = matrix

   def dimension(self):
       return len(self.matrix), len(self.matrix[0])

   def reduce_matrix(self, i, j):
       temp = self.matrix[:i-1] + self.matrix[i:]
       M = A([row[:j-1] + row[j:] for row in temp])
       return M

   def determinant(self):
       (nrows, ncols) = self.dimension()
       if nrows != ncols:
           return ("Cannot find determinant of non-square matrix.")
       elif nrows == 1:
           return self.matrix[0][0]
       else:
           M = A(sum([ ((-1)**j) * self.matrix[0][j] * self.reduce_matrix(1, 
                   j+1).determinant() for j in range(ncols) ]))
           return M

Hello, I just started OOP so I have a question regarding using the returned value of a method in place of the "instance name" that is passed as "self" for some other method.

I included the rest of the code that just makes the calculations for a matrix problem, but I'm only focusing on the " self.reduce_matrix(1, j+1)).determinant()" bit of it. I need to take a matrix (which is a list of lists ex. [[1,2,3],[4,5,6]] ), and perform the "reduce_matrix" method 1 time per column in the matrix, and each time, the "determinant(self)" method passes in the value returned from the other method. When I run it, it says that "list object has no attribute "determinant"" because I can't pass in "self" to the determinant method like I usually do --> "self.determinant(self)"

Any suggestions will be very appreciated

Answer 1

In reduce_matrix :

• create M as M = A([row[:j-1] + row[j:] for row in temp])
• do not return M.matrix but M itself.

That said, numpy is there for all kind of matrix operations and more.