Score Vowpal Wabbit Version 7-4 Model


Support for Machine Learning Studio (classic) will end on 31 August 2024. We recommend you transition to Azure Machine Learning by that date.

Beginning 1 December 2021, you will not be able to create new Machine Learning Studio (classic) resources. Through 31 August 2024, you can continue to use the existing Machine Learning Studio (classic) resources.

ML Studio (classic) documentation is being retired and may not be updated in the future.

Scores data using the Vowpal Wabbit machine learning system from the command line interface

Category: Text Analytics


Applies to: Machine Learning Studio (classic) only

Similar drag-and-drop modules are available in Azure Machine Learning designer.

Module overview

This article describes how to use the Score Vowpal Wabbit Version 7-4 Model module in Machine Learning Studio (classic), to generate scores for a set of input data, using an existing trained Vowpal Wabbit model.

This module is provided for compatibility with version 7-4 of the Vowpal Wabbit framework. Use this module only if you need to score data using a trained model that was saved in the 7-4 format.

To create a new VW model, we recommend that you use the latest version::

How to configure Score Vowpal Wabbit Version 7-4 Model

  1. Add the Score Vowpal Wabbit Version 7-4 Model module to your experiment.

  2. Add a trained Vowpal Wabbit model and connect it to the left-hand input port. You can use a trained model created in the same experiment, or locate a saved model in the Trained Models group of Studio (classic)’s left navigation pane.


    The model must be available in Machine Learning Studio (classic); you cannot directly load a model from Azure storage.

    Only Vowpal Wabbit 7-4 models are supported; you cannot connect saved models that were trained by using other algorithms, and you cannot use models that were trained using later versions.

  3. In the VW arguments text box, type a set of valid command-line arguments to the Vowpal Wabbit executable.

    For information about which Vowpal Wabbit arguments are supported in Machine Learning, see the Technical notes section.

  4. Click Specify data type, and select one of the supported data types from the list.

    Scoring requires a single column of VW-compatible data.

    If you have an existing file that was created in the SVMLight or VW formats, you can load it into the Azure ML workspace as a new dataset in one of these formats: Generic CSV without header, TSV without header.

    The VW option requires that a label be present, but it is not used in scoring except for comparison.

  5. Add an Import Data module and connect it to the right-hand input port of Score Vowpal Wabbit Version 7-4. Configure the Import Data module to access the input data.

    The input data for scoring must have been prepared ahead of time in one of the supported formats and stored in Azure blob storage.

  6. Select the option, Include an extra column containing labels, if you want to output labels together with the scores.

    Typically, when handling text data, Vowpal Wabbit does not require labels, and will return only the scores for each row of data.

  7. Select the option, Use cached results, if you want to re-use results from a previous run, assuming the following conditions are met:

    • A valid cache exists from a previous run.

    • The input data and parameters settings of the module have not changed since the previous run.

    Otherwise, the import process is repeated each time the experiment runs.

  8. Run the experiment.


After training is complete:

The output indicates a prediction score normalized from 0 to 1.


For examples of how Vowpal Wabbit can be used in machine learning, see the Azure AI Gallery:

  • Vowpal Wabbit sample

    This experiment demonstrates data preparation, training, and operationalization of a VW model.

The following video provides a walkthrough of the training and scoring process for Vowpal Wabbit:

Technical notes

This section contains implementation details, tips, and answers to frequently asked questions.

Supported and unsupported parameters

Vowpal Wabbit has many command-line options for choosing and tuning algorithms. A full discussion of these options is not possible here; we recommend that you view the Vowpal Wabbit wiki page.

The following parameters are not supported in Machine Learning Studio (classic).

  • The input/output options specified in

    These properties are already configured automatically by the module.

  • Additionally, any option that generates multiple outputs or takes multiple inputs is disallowed. These include --cbt, --lda, and --wap.

  • Only supervised learning algorithms are supported. This disallows these options: –active, --rank, --search etc.

All arguments other than those described above are allowed.

Expected inputs

Name Type Description
Trained model ILearner interface Trained learner
Dataset Data Table Dataset to be scored

Module parameters

Name Range Type Default Description
VW arguments Any String Type Vowpal Wabbit arguments.

The following arguments are not supported:

- -i
- -p or
- -t
Include an extra column containing labels Any Boolean false Specify whether the zipped file should include labels with the predictions
Specify data type VW

DataType VW Indicate whether the file format is SVMLight or Vowpal Wabbit


Name Type Description
Results dataset Data Table Dataset with the prediction results


Exception Description
Error 0001 Exception occurs if one or more specified columns of data set couldn't be found.
Error 0003 Exception occurs if one or more of inputs are null or empty.
Error 0004 Exception occurs if parameter is less than or equal to specific value.
Error 0017 Exception occurs if one or more specified columns have type unsupported by current module.

For a list of errors specific to Studio (classic) modules, see Machine Learning Error codes.

For a list of API exceptions, see Machine Learning REST API Error Codes.

See also

Text Analytics
Feature Hashing
Named Entity Recognition
Vowpal Wabbit Score
Train Vowpal Wabbit 7-4 Model
Train Vowpal Wabbit 7-10 Model
A-Z Module List