'Regression Tree can handle sparse data.
GH-2497'

def test_sparse_data_regression(self):

    table1 = Table('housing')
    self.send_signal('Data', table1)
    model_dense = self.get_output('Model')
    table2 = Table('housing')
    table2.X = sp.csr_matrix(table2.X)
    self.send_signal('Data', table2)
    model_sparse = self.get_output('Model')
    self.assertTrue(np.array_equal(model_dense._code, model_sparse._code))
    self.assertTrue(np.array_equal(model_dense._values, model_sparse._values))
