Tensorflow Model Analysis Setup

Configuration

TFMA stores its configuration in a proto that is serialized to JSON. This proto consolidates the configuration required for input data, output data, model specifications, metric specifications, and slicing specifications.

All TFMA pipelines are associated with a baseline (primary) model and zero or more candidate (secondary) models. The baseline and candidate model are defined by the user at the start of the pipeline and each require a unique name. The following are examples of typical configuration setups a user may use:

  • Single model evaluation:
    • N/A (i.e. no name)
  • Validation-based evaluation:
    • baseline
    • candidate
  • Model comparison evaluation:
    • my_model_a
    • my_model_b

Model Specs

Model specs are of type tfma.ModelSpec and are used to define the location of a model as well as other model specific parameters. For example the following are typical settings that would need to be configured prior to running an evaluation:

  • name - name of model (if multiple models used)
  • signature_name - name of signature used for predictions (default is serving_default). Use eval if using an EvalSavedModel.
  • label_key - name of the feature associated with the label.
  • example_weight_key - name of the feature assocated with the example weight.

Metrics Specs

Metrics specs are of type tfma.MetricsSpec and are used to configure the metrics that will be calculated as part of the evaluation. Different machine learning problems use different types of metrics and TFMA offers a lot of options for configuring and customizing the metrics that are computed. Since metrics are a very large part of TFMA, they are discussed in detail separately in metrics.

Slicing Specs

Slicing specs are of type tfma.SlicingSpec and are used to configure the slices criteria that will be used during the evaluation. Slicing can be done either by feature_keys, feature_values, or both. Some examples of slicing specs are as follows:

  • {}
    • Slice consisting of overall data.
  • { feature_keys: ["country"] }
    • Slices for all values in feature "country". For example, we might get slices "country:us", "country:jp", etc.
  • { feature_values: [{key: "country", value: "us"}] }
    • Slice consisting of "country:us".
  • { feature_keys: ["country", "city"] }
    • Slices for all values in feature "country" crossed with all values in feature "city" (note this may be expensive).
  • { feature_keys: ["country"] feature_values: [{key: "age", value: "20"}] }
    • Slices for all values in feature "country" crossed with value "age:20"

EvalSharedModel

In addition to the configuration settings, TFMA also requires that an instance of a tfma.EvalSharedModel be created for sharing a model between multiple threads in the same process. The shared model instance includes information about the type of model (keras, etc) and how to load and configure the model from its saved location on disk (e.g. tags, etc). The tfma.default_eval_shared_model API can be used to create a default instance given a path and set of tags.