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Saving and loading models

You save a trained classifier with the -d option (dumping), e.g.:

 java weka.classifiers.trees.J48 -C 0.25 -M 2 -t /some/where/train.arff -d /other/place/j48.model
And you can load it with -l and use it on a test set, e.g.:

 java weka.classifiers.trees.J48 -l /other/place/j48.model -T /some/where/test.arff
Note, when loading a model you no longer need to supply specific parameters to the classifier.


A trained model can be saved like this, e.g., J48:

  • train your model on the training data /some/where/train.arff
  • right-click in the Results list on the item which model you want to save
  • select Save model and save it to /other/place/j48.model

You can load the previously saved model with the following steps:

  • load your test data /some/where/test.arff via the Supplied test set button
  • right-click in the Results list, select Load model and choose /other/place/j48.model
  • in the More options dialog, change the Output predictions to CSV or another format (and specify a file in the options of the output format), if you want to store the predictions in a file rather than having to copy/paste them
  • select Re-evaluate model on current test set

Based on this Weka Mailing List post.

Making Predictions with your model without retraining#

See the Making predictions article for detailed information.

Source code#

See Serialization for code examples.

See also#