matrix.py

#implementation of the Matrix ADT using 2-D array

from my2darray import Array2D

class Matrix:
    def __init__(self, numRows, numcols):
        self._theGrid = Array2D(numRows, numCols)
        self._theGrid.clear(0)

    def numRows(self):
        return self._theGrid.numRows()

    def numCols(self):
        return self._theGrid.numCols()

    def __getitem__(self, ndxTuple):
        return self._theGrid[ndxTuple[0], ndxTuple[1]]

    def __setitem__(self, ndxTuple, scalar):
        self._theGrid[ndxTuple[0],ndxTuple[1]]=scalar

    def scaleBy(self, scalar):
        for r in range(self.numRows()):
            for c in range(self.numCols()):
                self[r,c] *= scalar

    def __add__(self, rhsMatrix):
        assert rhsMatrix.numRows() == self.numRows() and \
            rhsMatrix.numCols() == self.numCols(), \
            "Matrix size not compatible for adding"
        newMatrix = Matrix(self.numRows(), self.numCols())
        for r in range(self.numRows()):
            for c in range(self.numCols()):
                newMatrix[r, c] = self[r,c] + rhsMatrix[r,c]
        return newMatrix

    def __sub__(self, rhsMatrix):
        assert rhsMatrix.numRows() == self.numRows() and \
            rhsMatrix.numCols() == self.numCols(), \
            "Matrix size not compatible for adding"
        newMatrix = Matrix(self.numRows(), self.numCols())
        for r in range(self.numRows()):
            for c in range(self.numCols()):
                newMatrix[r, c] = self[r,c] - rhsMatrix[r,c]
        return newMatrix