Update phishing_email_detection_gpt2.py

Set NAS to minimize Perplexity.

Author: david-thrower

phishing_email_detection_gpt2.py

@@ -570,8 +570,8 @@ def reset_state(self):
     training_data=x_train_packaged,
     labels=y_train_packaged,
     validation_split=0.2,
-    direction='maximize',
-    metric_to_rank_by="val_categorical_accuracy",
+    direction='minimize',
+    metric_to_rank_by="perplexity", # REPLACE WITH VAL PERPLEXITY ONCE THIS IS STABLE
     minimum_levels=minimum_levels,
     maximum_levels=maximum_levels,
     minimum_units_per_level=minimum_units_per_level,