44 lines
2.0 KiB
Markdown
44 lines
2.0 KiB
Markdown
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# blt-gp
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Genetic Programming (GP) library for C++. Integrates directly into the C++ type system, a safe replacement for lilgp without performance compromises.
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## Easy to use, Safe, and fast, all without compromise
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Using blt-gp is very easy, import the program header, define your operators, and then call the relevant functions to set up the program to your liking.
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Concrete examples can be found in the example folder and compiled using the CMake argument `-DBUILD_EXAMPLES=ON`
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Operator example:
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```c++
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// constructor takes an optional string that describes the function of the operator. Used in printing.
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blt::gp::operation_t add([](float a, float b) {
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return a + b;
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}, "add");
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```
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Operators can return different types or have differing types as arguments, this will automatically be recognized by the library.
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```c++
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// Any callable type can be passed as the function parameter
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// so long as the function exists for the lifetime of the gp_program object.
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bool compare_impl(bool type, float a, float b)
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{
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return type ? (a > b) : (a < b);
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}
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blt::gp::operation_t compare(compare_impl, "compare");
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```
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Please note that if a type doesn't have a way to produce a terminal, or doesn't have a way of converting from a type that has a terminal, you will get an error.
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Defining your fitness function is just as easy:
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```c++
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const auto fitness_function = [](blt::gp::tree_t& current_tree, blt::gp::fitness_t& fitness, blt::size_t current_index) {
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// evaluate your fitness
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// ...
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// write to the fitness out parameter. Only "adjusted_fitness" is used during evaluation.
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fitness.raw_fitness = static_cast<double>(fitness.hits);
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fitness.standardized_fitness = fitness.raw_fitness;
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// higher values = better. Should be bounded [0, 1]
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fitness.adjusted_fitness = 1.0 - (1.0 / (1.0 + fitness.standardized_fitness));
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// returning true from this function ends the evaluation of the program, as this signals that a valid solution was found.
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// this function is allowed to return void.
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return static_cast<blt::size_t>(fitness.hits) == training_cases.size();
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};
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```
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