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A Simple Genetic Solver in Rust (Rustlang) -- see blog post https://handcraftsman.wordpress.com/2015/05/14/a-simple-genetic-solver-in-rust-rustlang/
[package]
name = "genetic"
version = "0.0.1"
authors = ["Clinton <sheppard@cs.unm.edu>"]
[dependencies]
rand = "*"
time = "*"
extern crate time;
extern crate rand;
use rand::{thread_rng, sample, Rng};
use time::PreciseTime;
fn main() {
let start = PreciseTime::now();
let gene_set = " abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!.";
let target = "Not all those who wander are lost.";
let best = get_best(get_fitness, display, target, gene_set, target.len(), start);
println!("{}", best);
println!("Total time: {}", start.to(PreciseTime::now()));
}
fn get_best(get_fitness: fn(&String,&str) -> usize, display: fn(&String, &str, start: time::PreciseTime), target: &str, gene_set: &str, length: usize, start: time::PreciseTime) -> String {
let mut best_parent = generate_parent(gene_set, length);
let mut best_fitness = get_fitness(&best_parent, target);
while best_fitness < length {
let child = mutate_parent(&best_parent, gene_set);
let fitness = get_fitness(&child, target);
if fitness > best_fitness {
best_fitness = fitness;
best_parent = child;
display(&best_parent, target, start);
}
}
best_parent
}
fn generate_parent(gene_set: &str, length: usize) -> String {
let mut rng = thread_rng();
let sample = sample(&mut rng, gene_set.chars(), length);
sample.into_iter().collect()
}
fn mutate_parent(parent: &String, gene_set: &str) -> String {
let mut rng = thread_rng();
let gene_index = rng.gen::<usize>() % gene_set.len();
let parent_index = rng.gen::<usize>() % parent.len();
let mut candidate = String::with_capacity(parent.len());
if parent_index > 0 {
candidate.push_str(&parent[..parent_index]);
}
candidate.push_str(&gene_set[gene_index..(1+gene_index)]);
if parent_index+1 < parent.len() {
candidate.push_str(&parent[parent_index+1..]);
}
candidate
}
fn get_fitness(candidate: &String, target: &str) -> usize {
let different_count = target.chars()
.zip(candidate.chars())
.filter(|&(a, b)| a != b)
.count();
target.len() - different_count
}
fn display(candidate: &String, target: &str, start: time::PreciseTime) {
let now = PreciseTime::now();
let elapsed = start.to(now);
println!("{}\t{}\t{}", candidate, get_fitness(&candidate, target),elapsed);
}
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