code: def test_simple_grnn(self):
      dataset = datasets.load_diabetes()
      x_train, x_test, y_train, y_test = train_test_split(
          dataset.data, dataset.target, test_size=0.3
      )
  
      x_train_before = x_train.copy()
      x_test_before = x_test.copy()
      y_train_before = y_train.copy()
  
      grnnet = algorithms.GRNN(std=0.1, verbose=False)
      grnnet.train(x_train, y_train)
      result = grnnet.predict(x_test)
      error = metrics.mean_absolute_error(result, y_test)
  
      old_result = result.copy()
      self.assertAlmostEqual(error, 46.3358, places=4)
  
      # Test problem with variable links
      np.testing.assert_array_equal(x_train, x_train_before)
      np.testing.assert_array_equal(x_test, x_test_before)
      np.testing.assert_array_equal(y_train, y_train_before)
  
      x_train[:, :] = 0
      result = grnnet.predict(x_test)
  
      np.testing.assert_array_almost_equal(result, old_result)
      self.assertPickledNetwork(grnnet, x_test)
  
file_path: neupy/tests/algorithms/rbfn/test_grnn.py
imports: import numpy
  from sklearn import datasets, metrics
  from sklearn.model_selection import train_test_split
  from neupy import algorithms
  from neupy.exceptions import NotTrained
  from base import BaseTestCase
label_desc: Use image node_id 2 for calling the GRNNTestCase obj's underlying member method code with example usage: obj.test_simple_grnn() without return types