Policies

These docs are for version 1.x of Rasa Open Source.

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viewing: 1.10.1

Policies

Configuring Policies

The rasa.core.policies.Policy class decides which action to take at every step in the conversation.

There are different policies to choose from, and you can include multiple policies in a single rasa.core.agent.Agent.

Max History

One important hyperparameter for Rasa Core policies is the max_history. This controls how much dialogue history the model looks at to decide which action to take next.

Data Augmentation

When you train a model, by default Rasa Core will create longer stories by randomly gluing together the ones in your stories files.

Action Selection

At every turn, each policy defined in your configuration will predict a next action with a certain confidence level. For more information about how each policy makes its decision, read into the policy’s description below.

Keras Policy

The KerasPolicy uses a neural network implemented in Keras to select the next action.

Embedding Policy

Warning EmbeddingPolicy was renamed to TEDPolicy. Please use TED Policy instead of EmbeddingPolicy in your policy configuration. The functionality of the policy stayed the same.

TED Policy

The Transformer Embedding Dialogue (TED) Policy is described in our paper.

Mapping Policy

The MappingPolicy can be used to directly map intents to actions.

Memoization Policy

The MemoizationPolicy just memorizes the conversations in your training data.

Augmented Memoization Policy

The AugmentedMemoizationPolicy remembers examples from training stories for up to max_history turns.

Fallback Policy

The FallbackPolicy invokes a fallback action if at least one of the following occurs:

  1. The intent recognition has a confidence below nlu_threshold.
  2. The highest ranked intent differs in confidence with the second highest ranked intent by less than ambiguity_threshold.
  3. None of the dialogue policies predict an action with confidence higher than core_threshold.

Two-Stage Fallback Policy

The TwoStageFallbackPolicy handles low NLU confidence in multiple stages by trying to disambiguate the user input.

Form Policy

The FormPolicy is an extension of the MemoizationPolicy which handles the filling of forms. Once a FormAction is called, the FormPolicy will continually predict the FormAction until all required slots in the form are filled.