code: def _epoch_as_matrix(dataset):
      return np.vstack([x.numpy() for x in dataset])
  
file_path: stellargraph/tests/mapper/test_graphwave_generator.py
imports: from stellargraph.core.graph import *
  from stellargraph.mapper.graphwave_generator import GraphWaveGenerator, _empirical_characteristic_function
  from ..test_utils.graphs import barbell
  import numpy
  import pytest
  import scipy.sparse
  import tensorflow
label_desc: Use image node_id 1 for calling a global function with example usage: _epoch_as_matrix(dataset) and returns: np