Migrating a Legacy Model

Automatic Migration on Load

InstanceSpace.load and exploreIS migrate a legacy model in memory each time they load it. Nothing is written to disk:

obj = InstanceSpace.load('/path/to/old/run/');   % migrated in memory
obj = obj.explore('/path/to/new/instances/');

Converting the File Once

To avoid repeating the migration, including any classifier retraining, on every load, convert the file:

ISAmigrateModel('/path/to/old/run/');

The original is kept as model_legacy.mat. Choose another backup name with ISAmigrateModel(rootdir,'backupSuffix','_v08').

What Changes

• Options are renamed to the current groups: opts.oracle → opts.pythia, opts.pbldr → opts.pilot, opts.sbound → opts.cloister, opts.footprint → opts.trace, and opts.perf.MaxMin → opts.perf.MaxPerf. The feature-selection flags of opts.corr and opts.clust move to opts.sifted.
• Classifiers. LIBSVM models cannot be evaluated by the current code. They are retrained with the classifier in opts.pythia.classifier ('knn' if unset) on the training data stored in the model. Predictions of the retrained model can differ slightly from those of the original.
• Footprints in the old DBSCAN/polyshape format are recomputed with TRACE3. Their areas, densities and purities can differ from the values reported by the old version.
• Field names such as data.bestPerformace are corrected.

The complete table is on the ISAmigrateModel reference page.

When Migration Cannot Complete

• A projection without its reconstruction matrices (model.pilot.B, model.pilot.C) is kept as is, with a warning.
• Retraining LIBSVM classifiers and recomputing footprints need the training data stored in the model (model.pilot.Z and model.data). When it is missing, the fields are renamed only, with a warning.
• If a LIBSVM model has to be evaluated as-is, PYTHIA raises ISA:PYTHIA:noLibsvm unless the LIBSVM MEX files are on the path. The toolbox does not include them; get them from the LIBSVM project. Retraining is recommended instead.