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Anatomy of a tagger definition

A tagger definition's YAML file is made up of distinct sections. You are encouraged to reference this guide as you create and edit your first tagger definition.

1. Variables​

A section that specifies the tagger's inputs.

Variable name​

An identifier used to reference the variable in later sections.

Source channel​

The robolog channel from which the variable's value is sourced.

Access path​

The data path accessing a value or complex type within a message.

Tip: The path should be specific, ending on a value and not a sub-component of the data structure whenever possible. This reduces the amount of compute time required to run the tagger.

Rolling window​

An optional feature that allows you to specify a rolling window of data to be used in the calculation of the variable's value. The rolling window is defined by the following parameters:

Direction​

The direction of the rolling window—either "look_ahead" or "look_back".

Unit​

The unit of time to be used—either "seconds" or "frames".

Size​

The number of units to be included in the rolling window.

Import dependencies​

An optional Python code block you may use to import built-in modules and define functions you intend to use in the rolling function's calculation.

Rolling function​

The window function used to calculate the variable's value.

2. Predicates​

A section containing rules—specified as expressions evaluating to a boolean value—that must all be true during the event.

Predicate name​

An identifier used to reference the predicate in later sections.

Import​

An optional Python code block that you may use to import built-in modules and to define functions that you intend to use in the predicate's Calculate section.

Calculate​

An optional Python code block you may use to calculate intermediate values referred to in the Evaluate section.

Evaluate​

An expression that must evaluate to a boolean value. The expression may reference any variables defined in the tagger definition's Variables section, as well as any intermediate values calculated in the predicate's Calculate section.

3. Outputs​

A section specifying the metadata value(s) created for each identified event.

Output Name​

A name that uniquely identifies the output.

Field alias​

The metadata field's alias for which a new value is created.

Note: While our web UI allows you to select the field via its alias from a dropdown menu, the field's ID is used in the YAML definition.

Type​

Specifies whether the metadata created is static—using a value you provide within the definition—or dynamic—using a function applied to the data corresponding to each event instance.