code: def test_matrix_indexing(self):
      # Tests conversions and indexing
      x1 = np.matrix([[1, 2, 3], [4, 3, 2]])
      x2 = masked_array(x1, mask=[[1, 0, 0], [0, 1, 0]])
      x3 = masked_array(x1, mask=[[0, 1, 0], [1, 0, 0]])
      x4 = masked_array(x1)
      # test conversion to strings
      str(x2)  # raises?
      repr(x2)  # raises?
      # tests of indexing
      assert_(type(x2[1, 0]) is type(x1[1, 0]))
      assert_(x1[1, 0] == x2[1, 0])
      assert_(x2[1, 1] is masked)
      assert_equal(x1[0, 2], x2[0, 2])
      assert_equal(x1[0, 1:], x2[0, 1:])
      assert_equal(x1[:, 2], x2[:, 2])
      assert_equal(x1[:], x2[:])
      assert_equal(x1[1:], x3[1:])
      x1[0, 2] = 9
      x2[0, 2] = 9
      assert_equal(x1, x2)
      x1[0, 1:] = 99
      x2[0, 1:] = 99
      assert_equal(x1, x2)
      x2[0, 1] = masked
      assert_equal(x1, x2)
      x2[0, 1:] = masked
      assert_equal(x1, x2)
      x2[0, :] = x1[0, :]
      x2[0, 1] = masked
      assert_(allequal(getmask(x2), np.array([[0, 1, 0], [0, 1, 0]])))
      x3[1, :] = masked_array([1, 2, 3], [1, 1, 0])
      assert_(allequal(getmask(x3)[1], masked_array([1, 1, 0])))
      assert_(allequal(getmask(x3[1]), masked_array([1, 1, 0])))
      x4[1, :] = masked_array([1, 2, 3], [1, 1, 0])
      assert_(allequal(getmask(x4[1]), masked_array([1, 1, 0])))
      assert_(allequal(x4[1], masked_array([1, 2, 3])))
      x1 = np.matrix(np.arange(5) * 1.0)
      x2 = masked_values(x1, 3.0)
      assert_equal(x1, x2)
      assert_(
          allequal(
              masked_array([0, 0, 0, 1, 0], dtype=MaskType), x2.mask
          )
      )
      assert_equal(3.0, x2.fill_value)
  
imports: import pickle
  import numpy
  from numpy.testing import assert_warns
  from numpy.ma.testutils import assert_, assert_equal, assert_raises, assert_array_equal
  from numpy.ma.core import masked_array, masked_values, masked, allequal, MaskType, getmask, MaskedArray, nomask, log, add, hypot, divide
  from numpy.ma.extras import mr_
label_desc: Use image node_id 1 for calling the TestMaskedMatrix obj's underlying member method code with example usage: obj.test_matrix_indexing() without return types