CODEWITHSUNDEEP
pythonmatrixmultiplication
Julian Ailan
Julian Ailan

Reputation: 15

Problems with Matrix Multiplication

I'm having some troubles when it comes to multiplying two matrices. An AttributeError appears when I'm trying to perform the addition part

Traceback (most recent call last):
  File "MatrixClass.py", line 189, in <module>
    main()
  File "MatrixClass.py", line 184, in main
    mat.multiplyMatrixes(mat1,mat2)
  File "MatrixClass.py", line 176, in multiplyMatrixes
    self[i][j] += (m1[i][k])*(m2[k][j]) 
AttributeError: matrix instance has no attribute '__getitem__'

I tried saving the new matrix in another instance called for example m3 but the I thought it would be better to use self instead.

Here's my code:

def multiplyMatrices(self,m1,m2):
    if m1.getRows() == m2.getColumns() and m1.getColumns() == m2.getRows():
        self.setRows()
        self.setColumns()
        for i in range(m1.getRows()):
            for j in range(m2.getColumns()):
                for k in range(m1.getColumns()):
                    self[i][j] += (m1[i][k])*(m2[k][j])

I created the instance of self in main(), before calling multiplyMatrices()

Upvotes: 0

Views: 227

Answers (1)

ubomb
ubomb

Reputation: 11681

According to the AttributeError, you never defined the __getitem__ method in your class. This is how you can control object[key] access. I would suggest reading up on the python data model in general if you are deciding to make a more advanced class (like this one) in python. Although it is a bit strange to have the multiplication of two other matrices being stored in self. I'd probably just create a new matrix in the method and return that.

Upvotes: 1

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