Method getFeatureWeights

src/openms/source/ANALYSIS/SVM/SimpleSVM.cpp:288–318

only works in classification mode

// only works in classification mode
void SimpleSVM::getFeatureWeights(map<String, double>& feature_weights) const
{
  if (model_ == nullptr)
  {
    throw Exception::Precondition(__FILE__, __LINE__, OPENMS_PRETTY_FUNCTION,
                                  "SVM model has not been trained (use the "
                                  "'setup' method)");
  }
  Size k = model_->nr_class;
  if (k > 2)
  {
    throw Exception::Precondition(__FILE__, __LINE__, OPENMS_PRETTY_FUNCTION,
                                  "Output of feature weights is currently only "
                                  "supported for two-class classification");
  }

  feature_weights.clear();
  Size n_sv = model_->l; // number of support vectors
  for (Size l = 0; l < n_sv; ++l)
  {
    double sv_coef = model_->sv_coef[0][l];
    // LIBSVM uses a sparse representation for data (incl. support vectors):
    for (Size n = 0; ; ++n)
    {
      const struct svm_node& node = model_->SV[l][n];
      if (node.index == -1) break;
      const String& predictor_name = predictor_names_[node.index - 1];
      feature_weights[predictor_name] += sv_coef * node.value;
    }
  }
}

void SimpleSVM::scaleData_(PredictorMap& predictors)
{