The ML.GLOBAL_EXPLAIN function

This document describes the ML.GLOBAL_EXPLAIN function, which lets you provide explanations for the entire model by aggregating the local explanations of the evaluation data. You can only use ML.GLOBAL_EXPLAIN with models that are trained with the ENABLE_GLOBAL_EXPLAIN option set to TRUE.

Syntax

ML.GLOBAL_EXPLAIN(
  MODEL `PROJECT_ID.DATASET.MODEL`,
  STRUCT(
    [CLASS_LEVEL_EXPLAIN AS class_level_explain]))

Arguments

ML.GLOBAL_EXPLAIN takes the following arguments:

  • PROJECT_ID: your project ID.
  • DATASET: the BigQuery dataset that contains the model.
  • MODEL: the name of the model.

  • CLASS_LEVEL_EXPLAIN: a BOOL value that specifies whether global feature importances are returned for each class. Applies only to non-AutoML Tables classification models. When set to FALSE, the global feature importance of the entire model is returned rather than that of each class. The default value is FALSE.

    Regression models and AutoML Tables classification models only have model-level global feature importance.

Output

The output of ML.GLOBAL_EXPLAIN has two formats:

  • For classification models with class_level_explain set to FALSE, and for regression models, the following columns are returned:

    • feature: a STRING value that contains the feature name.
    • attribution: a FLOAT64 value that contains the feature importance to the model overall.

  • For classification models with class_level_explain set to TRUE, the following columns are returned:

    • <class_name>: a STRING value that contains the name of the class in the label column.
    • feature: a STRING value that contains the feature name.
    • attribution: a FLOAT64 value that contains the feature importance to this class.

    For each class, only the top 10 most important features are returned.

Examples

The following examples assume your model is in your default project.

Regression model

This example gets global feature importance for the boosted tree regression model mymodel in mydataset. The dataset is in your default project.

SELECT
  *
FROM
  ML.GLOBAL_EXPLAIN(MODEL `mydataset.mymodel`)

Classifier model

This example gets global feature importance for the boosted tree classifier model mymodel in mydataset. The dataset is in your default project.

SELECT
  *
FROM
  ML.GLOBAL_EXPLAIN(MODEL `mydataset.mymodel`, STRUCT(TRUE AS class_level_explain))

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