Add a unit test

    np.testing.assert_array_equal(

        np.stack([dataset.y[:, 0], dataset.X[:, 0]], axis=1), dataset3.w)

if __name__ == "__main__":

  unittest.main()

  def test_to_str(self):

    """Tests to string representation of Dataset."""

    dataset = dc.data.NumpyDataset(

        X=np.random.rand(5, 3), y=np.random.rand(5,), ids=np.arange(5))

    ref_str = '<NumpyDataset X.shape: (5, 3), y.shape: (5,), w.shape: (5,), ids: [0 1 2 3 4], task_names: [0]>'

    assert str(dataset) == ref_str

    # Test id shrinkage

    dc.utils.set_print_threshold(10)

    dataset = dc.data.NumpyDataset(

        X=np.random.rand(50, 3), y=np.random.rand(50,), ids=np.arange(50))

    ref_str = '<NumpyDataset X.shape: (50, 3), y.shape: (50,), w.shape: (50,), ids: [0 1 2 ... 47 48 49], task_names: [0]>'

    assert str(dataset) == ref_str

    # Test task shrinkage

    dataset = dc.data.NumpyDataset(

        X=np.random.rand(50, 3), y=np.random.rand(50, 20), ids=np.arange(50))

    ref_str = '<NumpyDataset X.shape: (50, 3), y.shape: (50, 20), w.shape: (50, 1), ids: [0 1 2 ... 47 48 49], task_names: [ 0  1  2 ... 17 18 19]>'

    assert str(dataset) == ref_str