private void fillAttributes() {
   int layerIdx = nnet.getLayersCount() - 1; // output layerIdx by default
   Attribute attr1;
   Attribute attr2 = null;
   if (layerCombo.isEnabled()) {
     layerIdx = (Integer) layerCombo.getSelectedItem() - 1;
   }
   attr1 = new Attribute(layerIdx, false, "Layer");
   if (attributeTxtField.isEnabled()) {
     attribute = Integer.parseInt(attributeTxtField.getText());
     attr2 = new Attribute(attribute, false, "Input");
   }
   graphBuilder.setAttribute1(attr1);
   graphBuilder.setAttribute2(attr2);
   outputNeuronCount = nnet.getLayerAt(layerIdx).getNeuronsCount();
 }