alogos.systems.cfggp.mutation

Mutation functions for CFG-GP.

Functions

subtree_replacement(grammar, genotype, parameters=None)

Change a randomly chosen node by attaching a randomly generated subtree.

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Detailed object descriptions

alogos.systems.cfggp.mutation.subtree_replacement(grammar, genotype, parameters=None)

Change a randomly chosen node by attaching a randomly generated subtree.

Parameters:

• grammar (Grammar)

• genotype (Genotype)

• parameters (dict or ParameterCollection, optional) – Following keyword-value pairs are considered by this function:

  • max_depth (int) : Maximum tree depth.

Returns:

genotype (Genotype) – Mutated genotype.

References

• Grammatically-based Genetic Programming (1995)

  • “Mutation applies to a single program. A program is selected for mutation, and one non-terminal is randomly selected as the site for mutation. The tree below this non-terminal is deleted, and a new tree randomly generated from the grammar using this non-terminal as a starting point. The tree is limited in total depth by the current maximum allowable program depth (MAX-TREE-DEPTH), in an operation similar to creating the initial population.”