193 lines
7.3 KiB
C++
193 lines
7.3 KiB
C++
#pragma once
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/*
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* Copyright (C) 2024 Brett Terpstra
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef BLT_GP_TRANSFORMERS_H
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#define BLT_GP_TRANSFORMERS_H
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#include <blt/std/utility.h>
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#include <blt/gp/fwdecl.h>
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#include <blt/gp/tree.h>
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#include <blt/gp/generators.h>
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#include <blt/std/expected.h>
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#include <blt/meta/config_generator.h>
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namespace blt::gp
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{
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namespace detail
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{
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template<typename T>
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inline static constexpr double sum(const T& array)
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{
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double init = 0.0;
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for (double i : array)
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init += i;
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return init;
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}
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template<blt::size_t size, typename... Args>
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static constexpr std::array<double, size> aggregate_array(Args... list)
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{
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std::array<double, size> data{list...};
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auto total_prob = sum(data);
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double sum_of_prob = 0;
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for (auto& d : data)
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{
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auto prob = d / total_prob;
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d = prob + sum_of_prob;
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sum_of_prob += prob;
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}
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return data;
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}
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}
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class crossover_t
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{
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public:
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struct point_info_t
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{
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blt::ptrdiff_t point;
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operator_info_t& type_operator_info;
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};
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struct crossover_point_t
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{
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blt::ptrdiff_t p1_crossover_point;
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blt::ptrdiff_t p2_crossover_point;
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};
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struct config_t
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{
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// number of times crossover will try to pick a valid point in the tree. this is purely based on the return type of the operators
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blt::u16 max_crossover_tries = 5;
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blt::f32 traverse_chance = 0.5;
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blt::u32 min_tree_size = 5;
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// legacy settings:
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// if we fail to find a point in the tree, should we search forward from the last point to the end of the operators?
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bool should_crossover_try_forward = false;
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// avoid selecting terminals when doing crossover
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bool avoid_terminals = false;
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};
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crossover_t() = default;
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explicit crossover_t(const config_t& config): config(config)
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{}
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std::optional<crossover_t::crossover_point_t> get_crossover_point(gp_program& program, const tree_t& c1, const tree_t& c2) const;
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std::optional<crossover_t::crossover_point_t> get_crossover_point_traverse(gp_program& program, const tree_t& c1, const tree_t& c2) const;
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std::optional<point_info_t> get_point_traverse(gp_program& program, const tree_t& t, std::optional<type_id> type) const;
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static std::optional<point_info_t> random_place_of_type(gp_program& program, const tree_t& t, type_id type);
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/**
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* child1 and child2 are copies of the parents, the result of selecting a crossover point and performing standard subtree crossover.
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* the parents are not modified during this process
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* @param program reference to the global program container responsible for managing these trees
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* @param p1 reference to the first parent
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* @param p2 reference to the second parent
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* @return expected pair of child otherwise returns error enum
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*/
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virtual bool apply(gp_program& program, const tree_t& p1, const tree_t& p2, tree_t& c1, tree_t& c2); // NOLINT
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virtual ~crossover_t() = default;
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protected:
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std::optional<point_info_t> get_point_traverse_retry(gp_program& program, const tree_t& t, std::optional<type_id> type) const;
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config_t config;
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};
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class mutation_t
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{
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public:
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struct config_t
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{
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blt::size_t replacement_min_depth = 2;
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blt::size_t replacement_max_depth = 6;
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std::reference_wrapper<tree_generator_t> generator;
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config_t(tree_generator_t& generator): generator(generator) // NOLINT
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{}
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config_t();
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};
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mutation_t() = default;
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explicit mutation_t(const config_t& config): config(config)
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{}
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virtual bool apply(gp_program& program, const tree_t& p, tree_t& c);
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// returns the point after the mutation
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blt::size_t mutate_point(gp_program& program, tree_t& c, blt::size_t node);
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virtual ~mutation_t() = default;
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protected:
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config_t config;
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};
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class advanced_mutation_t : public mutation_t
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{
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public:
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enum class mutation_operator : blt::i32
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{
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EXPRESSION, // Generate a new random expression
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ADJUST, // adjust the value of the type. (if it is a function it will mutate it to a different one)
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SUB_FUNC, // subexpression becomes argument to new random function. Other args are generated.
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JUMP_FUNC, // subexpression becomes this new node. Other arguments discarded.
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COPY, // node can become copy of another subexpression.
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END, // helper
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};
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advanced_mutation_t() = default;
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explicit advanced_mutation_t(const config_t& config): mutation_t(config)
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{}
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bool apply(gp_program& program, const tree_t& p, tree_t& c) final;
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advanced_mutation_t& set_per_node_mutation_chance(double v)
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{
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per_node_mutation_chance = v;
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return *this;
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}
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private:
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static constexpr auto operators_size = static_cast<blt::i32>(mutation_operator::END);
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private:
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// this value is adjusted inversely to the size of the tree.
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double per_node_mutation_chance = 5.0;
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static constexpr std::array<double, operators_size> mutation_operator_chances = detail::aggregate_array<operators_size>(
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0.25, // EXPRESSION
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0.15, // ADJUST
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0.01, // SUB_FUNC
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0.01, // JUMP_FUNC
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0.05 // COPY
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);
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};
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}
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#endif //BLT_GP_TRANSFORMERS_H
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