4. Advanced Features & Customization

library(E2E)
# Initialize systems for the examples
initialize_modeling_system_dia()
#> Diagnostic modeling system initialized and default models registered.
initialize_modeling_system_pro()
#> Prognosis modeling system initialized and default models registered.

Advanced Features

This guide covers advanced topics such as extending the E2E framework with custom models and interpreting model predictions using SHAP.

1. Extending the Framework: Adding New Models

The E2E framework is fully extensible. You can register your own custom models. For example, to add Adaboost for diagnosis:

# 1. Define the model function (must accept X, y, and other standard args)
ab_dia <- function(X, y, tune = FALSE, cv_folds = 5) {
  # Ensure caret is available
  if (!requireNamespace("caret", quietly = TRUE)) {
    stop("Package 'caret' is required for this custom model.")
  }
  ctrl <- caret::trainControl(method = "cv", number = cv_folds,
                              classProbs = TRUE, summaryFunction = caret::twoClassSummary)
  grid <- if (tune) {
    expand.grid(iter = c(50, 100), maxdepth = c(1, 2), nu = 0.1)
  } else {
    expand.grid(iter = 50, maxdepth = 1, nu = 0.1)
  }
  caret::train(x = X, y = y, method = "ada", metric = "ROC", trControl = ctrl, tuneGrid = grid)
}

# 2. Register the model with a unique name
register_model_dia("ab", ab_dia)

# 3. Now you can use "ab" in any diagnostic function
results_ab <- models_dia(train_dia, model = "ab")
#> Running model: ab
print_model_summary_dia("ab", results_ab$ab)
#> 
#> --- ab Model (on Training Data) Metrics ---
#> 
#> AUROC: 0.9994 (95% CI: 0.9987 - 1.0000)
#> AUPRC: 0.9999
#> Accuracy: 0.9919
#> F1: 0.9955
#> Precision: 0.9936
#> Recall: 0.9974
#> Specificity: 0.9375
#> --------------------------------------------------

2. Model Explanation with SHAP (figure_shap)

The figure_shap function provides model-agnostic explanations by calculating SHAP values. This reveals which features had the most impact on the model’s output.

Explaining a Diagnostic Model

# First, we need a model result object
bagging_xb_results <- bagging_dia(train_dia, base_model_name = "xb", n_estimators = 10, seed=123)
#> Running Bagging model: Bagging_dia (base: xb)

# Now, generate the SHAP explanation plot
figure_shap(
  data = bagging_xb_results,
  raw_data = train_dia,
  target_type = "diagnosis"
)
#> Training 'xgboost' surrogate model and calculating SHAP values...

Explaining a Prognostic Model

# First, we need a model result object
stacking_stepcox_pro_results <- stacking_pro(
  results_all_models = models_pro(train_pro, model = c("lasso_pro", "rsf_pro")),
  data = train_pro,
  meta_model_name = "stepcox_pro"
)
#> Running model: lasso_pro
#> Running model: rsf_pro
#> Running Stacking model: Stacking_pro (meta: stepcox_pro)

# Generate the SHAP explanation plot
figure_shap(
  data = stacking_stepcox_pro_results,
  raw_data = train_pro,
  target_type = "prognosis"
)
#> Training 'xgboost' surrogate model and calculating SHAP values...