code: def test_sofm_weight_init_exceptions(self):
      msg = "Cannot apply PCA"
      with self.assertRaisesRegexp(WeightInitializationError, msg):
          algorithms.SOFM(
              n_inputs=4,
              n_outputs=7,
              weight="init_pca",
              grid_type="hexagon",
          )
  
imports: import math
  import numpy
  from neupy import algorithms
  from neupy.exceptions import WeightInitializationError
  from neupy.algorithms.competitive import sofm
  from neupy.algorithms.competitive.neighbours import gaussian_df
  from base import BaseTestCase
label_desc: Use image node_id 1 for calling the SOFMWeightInitializationTestCase obj's underlying member method code with example usage: obj.test_sofm_weight_init_exceptions() without return types