Write your code: Minor of Matrix

Write a function that returns the Minor of Matrix of a 3x3 Matrix for a given line \((i)\) and column \((j)\)

Rules

1. Function returns a Numpy ndarray of shape=2x2

2. Function should work for all possible \(i,j\) combination

Solution

import numpy as np

def get_minor_ij(A, i, j):

    # write your code here

  File "/tmp/ipykernel_1917/1952751800.py", line 3
    # write your code here
                          ^
SyntaxError: unexpected EOF while parsing

A = np.array([[ 9, 12, 18],
              [ 2, -2,  5],
              [11,-17, 19]]
            )

get_minor_ij(A, 2, 3)

Testing

Check if your function returns the expected value using the cell below.

import unittest

class UnitTests(unittest.TestCase):
    def setUp(self):
        self.A = np.array([[ -7, 4, -2],
                           [ 2, -3,  5],
                           [-18, 10, 0]]
                         )

    def test_type(self):
        self.assertTrue(isinstance(get_minor_ij(A, 1, 2), np.ndarray), 'The function should return a NumPy array')
    def test_shape(self):
        self.assertTrue(get_minor_ij(self.A, 1, 2).shape == (2, 2), "The function should return an 2x2 array")
    def test_minor11(self):
        self.assertEqual(get_minor_ij(self.A, 1, 1).tolist(), [[-3, 5], [10,0]])
    def test_minor12(self):
        self.assertEqual(get_minor_ij(self.A, 1, 2).tolist(), [[2,5], [-18,0]])
    def test_minor13(self):
        self.assertEqual(get_minor_ij(self.A, 1, 3).tolist(), [[2,-3],[-18,10]])
    def test_minor21(self):
        self.assertEqual(get_minor_ij(self.A, 2, 1).tolist(), [[4,-2],[10,0]])
    def test_minor22(self):
        self.assertEqual(get_minor_ij(self.A, 2, 2).tolist(), [[-7,-2],[-18,0]])
    def test_minor23(self):
        self.assertEqual(get_minor_ij(self.A, 2, 3).tolist(), [[-7,4],[-18,10]])
    def test_minor31(self):
        self.assertEqual(get_minor_ij(self.A, 3, 1).tolist(), [[4,-2],[-3,5]])
    def test_minor32(self):
        self.assertEqual(get_minor_ij(self.A, 3, 2).tolist(), [[-7,-2],[2, 5]])
    def test_minor33(self):
        self.assertEqual(get_minor_ij(self.A, 3, 3).tolist(), [[-7,4],[2,-3]])

unittest.main(argv=[''], verbosity=2,exit=False)