From 8ec0d9ecc863e9b043c19b6a7ba6e1aa3d4b4bd9 Mon Sep 17 00:00:00 2001
From: Abdelghani Belgaid <72890326+abdelghanibelgaid@users.noreply.github.com>
Date: Thu, 28 Sep 2023 00:42:08 +0100
Subject: [PATCH] Update evaluation.py: Added a function to evaluate the
 performance of EM models on validation data using a specified metric.

---
 causalnex/evaluation/evaluation.py | 50 ++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/causalnex/evaluation/evaluation.py b/causalnex/evaluation/evaluation.py
index e0dd2aa..b2b1a03 100644
--- a/causalnex/evaluation/evaluation.py
+++ b/causalnex/evaluation/evaluation.py
@@ -32,6 +32,7 @@
 import pandas as pd
 from sklearn import metrics
 
+from causalnex.estimator import EMSingleLatentVariable
 from causalnex.network import BayesianNetwork
 
 
@@ -201,3 +202,52 @@ def classification_report(bn: BayesianNetwork, data: pd.DataFrame, node: str) ->
     )
 
     return report
+
+def evaluate_em_model(
+    em_model: EMSingleLatentVariable,
+    validation_data: pd.DataFrame,
+    metric: callable,
+    lv_column: str = None,
+):
+    """
+    Evaluate the performance of the learned EM model on validation data using a specified metric.
+
+    Args:
+        em_model (EMSingleLatentVariable): The trained EM model.
+        validation_data (pd.DataFrame): Validation dataset with the same structure as the training data.
+        metric (callable): A callable function or metric that takes two arguments: ground truth and predicted values.
+        lv_column (str): Name of the latent variable column in the dataset, if different from the one used during training.
+
+    Returns:
+        float: The computed evaluation metric value.
+
+    Example:
+    >>> em = EMSingleLatentVariable(sm=sm, data=train_data, lv_name=lv_name, node_states=node_states)
+    >>> em.run()  # Train the model
+    >>> validation_metric = evaluate_em_model(em, validation_data, custom_metric_function)
+    """
+    if validation_data.empty:
+        raise ValueError("Validation dataset is empty.")
+
+    if lv_column is None:
+        lv_column = em_model.lv_name
+
+    # Extract relevant columns from validation data
+    relevant_columns = [lv_column] + list(em_model.sm.successors(lv_column))
+    validation_data = validation_data[relevant_columns]
+
+    # Check if validation_data is still empty after column extraction
+    if validation_data.empty:
+        raise ValueError("Validation dataset does not contain relevant columns.")
+
+    # Compute the likelihood for each record in the validation data
+    likelihoods = []
+    for _, record in validation_data.iterrows():
+        likelihood = em_model.compute_likelihood(record.to_dict())
+        likelihoods.append(likelihood)
+
+    # Compute the evaluation metric by comparing the likelihoods with the true values
+    true_values = validation_data[lv_column]
+    evaluation_score = metric(true_values, likelihoods)
+
+    return evaluation_score