Update example 4

Co-authored-by: gvieralopez <[email protected]>

examples/example_04.py

@@ -14,23 +14,23 @@
     Dataset.uci_characters(),
     Dataset.uci_movement_libras(),
 ]
-
+
+# Select the desired features to be extracted from the trajectories
 featurizer = featurizers.UniversalFeaturizer()
 
 for dataset in datasets:
     print(f"\nDataset: {dataset.name}\n")
 
-    # Split the dataset into train and test
+    # Split the dataset into train and test and filter out short trajectories
     train, test = dataset.filter(
-        lambda traj, _: len(traj) >= 5 and traj.r.delta.norm.sum() > 0
+        lambda traj, label: len(traj) >= 5
+        and traj.r.delta.norm.sum() > 0
+        and dataset.label_counts[label] > 5
     ).split(
         train_size=0.7,
         random_state=SEED,
     )
 
-    # Select the desired features to be extracted from the trajectories
-    featurizer = featurizers.UniversalFeaturizer()
-
     # Define the model
     model = XGBoostModel(featurizer=featurizer)