Save and load trained models in ML.NET

Throughout the model building process, a model lives in memory and is accessible throughout the application’s lifecycle. However, once the application stops running, if the model is not saved somewhere locally or remotely, it’s no longer accessible. Typically models are used at some point after training in other applications either for inference or re-training. Therefore, it’s important to store the model.

Save a model locally

When saving a model you need two things:

  1. The ITransformer of the model.
  2. The DataViewSchema of the ITransformer‘s expected input.

After training the model, use the Save method to save the trained model to a file called using the DataViewSchema of the input data.

// Save Trained Model
mlContext.Model.Save(trainedModel, data.Schema, "");

Load a model stored locally

In a separate application or process, use the Load method along with the file path to get the trained model into your application.

//Define DataViewSchema for data preparation pipeline and trained model
DataViewSchema modelSchema;

// Load trained model
ITransformer trainedModel = mlContext.Model.Load("", out modelSchema);