refactoring regression model code

lib/tasks/stats.rake

@@ -63,11 +63,13 @@ namespace :stats do
 
     puts "\n✅ Graph generation completed!"
 
+    # remove old regressions for this model
+    model_name = "fa_fav_id_and_date"
+    TrainedRegressionModel.where(name: model_name).destroy_all
+
     # Save each regression model to the database
     regressions.each do |name, result|
       equation = result.equation
-      model_name = "fa_fav_id_and_date_#{name.downcase}"
-      TrainedRegressionModel.find_by(name: model_name)&.destroy
       TrainedRegressionModel.create!(
         name: model_name,
         model_type: name.downcase.tr(" ", "_"),