Python 8.11 to 9 migration

You can do nothing and everything should still work when migrating to VW 9. But if you want to move to the new way to avoid deprecation warnings and future breaks here’s a rundown.

Imports

Modules are now direcly accessible from the root module. In the past from vowpalwabbit import ... was needed, but now import vowpalwabbit and accessing with . will work.

pyvw

The old pyvw types are now available under the root module.

Instead of:

from vowpalwabbit import pyvw

Use:

import vowpalwabbit

And use the corresponding types exposed by vowpalwabbit instead of vowpalwabbit.pyvw.

Exception

vowpalwabbit.pyvw.SearchTask is only available under vowpalwabbit.pyvw due to its advanced nature and less usage.

DFtoVW

Replace any reference to the old module name DFtoVW with vowpalwabbit.dftovw.

sklearn_vw

Replace any reference to the old module name sklearn_vw with vowpalwabbit.sklearn.

Class names

• Replace vowpalwabbit.pyvw.vw with vowpalwabbit.Workspace

• Replace vowpalwabbit.pyvw.example with vowpalwabbit.Example

• Replace vowpalwabbit.pyvw.example_namespace with vowpalwabbit.ExampleNamespace

• Replace vowpalwabbit.pyvw.namespace_id with vowpalwabbit.NamespaceId

• Replace vowpalwabbit.pyvw.abstract_label with vowpalwabbit.AbstractLabel

• Replace vowpalwabbit.pyvw.simple_label with vowpalwabbit.SimpleLabel

• Replace vowpalwabbit.pyvw.multiclass_label with vowpalwabbit.MulticlassLabel

• Replace vowpalwabbit.pyvw.multiclass_probabilities_label with vowpalwabbit.MulticlassProbabilitiesLabel

• Replace vowpalwabbit.pyvw.cost_sensitive_label with vowpalwabbit.CostSensitiveLabel

• Replace vowpalwabbit.pyvw.cbandits_label with vowpalwabbit.CBLabel

get_prediction

Instead of calling the free function vowpalwabbit.pyvw.get_prediction() call vowpalwabbit.Example.get_prediction() on an vowpalwabbit.Example instance.

Label types and prediction types

• Instead of using the prediction type integer constants such as vowpalwabbit.pyvw.pylibvw.vw.pSCALAR use the corresponding value in vowpalwabbit.PredictionType

• Instead of using the label type integer constants such as vowpalwabbit.pyvw.pylibvw.vw.lSimple use the corresponding value in vowpalwabbit.LabelType

  • Instead of vowpalwabbit.pyvw.pylibvw.vw.lBinary use vowpalwabbit.LabelType.SCALAR

  • Instead of vowpalwabbit.pyvw.pylibvw.vw.lDefault use a value of None

  • vowpalwabbit.pyvw.pylibvw.vw.lMax did not have a corresponding type

Getting a label from an Example

• If using vowpalwabbit.Example.get_label(), you should change the parameter from a class type to a vowpalwabbit.LabelType.

• If calling vowpalwabbit.AbstractLabel.from_example(). This has changed from a method on an existing instance to a static factory function which accepts an vowpalwabbit.Example and returns an instance of the correspodning label type. Using vowpalwabbit.Example.get_label() is preferred.

ExampleNamespace.push_features

The first argument of vowpalwabbit.ExampleNamespace.push_features() was removed as it was not needed and unused. Using two arguments is deprecated, to fix the callsites remove the first argument.