feat(jssp): parameterize delay computation (#454)

- Add some important comments
- Parameterize delay_g calculation

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IF THERE IS NO LINKED ISSUE) -->

## Description

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## Linked issues

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linked to an issue -->

## Important implementation details

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examples/jssp/cli.rs

@@ -25,6 +25,10 @@ pub struct Args {
     #[arg(long = "popsize")]
     pub pop_size: Option<usize>,
 
+    /// The constant that appears in formula for delay in given iteration g.
+    /// Delay = Gene_{n+g} * delay_const_factor * maxdur. If not specified, defaults to 1.5.
+    pub delay_const_factor: Option<f64>,
+
     /// Path to config file with solver's parameters
     #[arg(short = 'c', long = "config")]
     pub cfg_file: Option<PathBuf>,

examples/jssp/config.rs

@@ -1,4 +1,10 @@
-use std::{fs::File, error::Error, io::{BufReader, self}, path::{PathBuf, Path}, fmt::Display};
+use std::{
+    error::Error,
+    fmt::Display,
+    fs::File,
+    io::{self, BufReader},
+    path::{Path, PathBuf},
+};
 
 use serde::Deserialize;
 
@@ -19,6 +25,10 @@ pub struct Config {
     /// Number of individuals in population. Set this if you want to
     /// override the default value computed basing on problem size
     pub pop_size: Option<usize>,
+
+    /// The constant that appears in formula for delay in given iteration g.
+    /// Delay = Gene_{n+g} * delay_const_factor * maxdur. If not specified, defaults to 1.5.
+    pub delay_const_factor: Option<f64>,
 }
 
 #[derive(Deserialize, Debug, Clone)]
@@ -27,6 +37,7 @@ pub struct PartialConfig {
     pub output_dir: Option<PathBuf>,
     pub n_gen: Option<usize>,
     pub pop_size: Option<usize>,
+    pub delay_const_factor: Option<f64>,
 }
 
 impl PartialConfig {
@@ -36,6 +47,7 @@ impl PartialConfig {
             output_dir: None,
             n_gen: None,
             pop_size: None,
+            delay_const_factor: None,
         }
     }
 }
@@ -65,6 +77,7 @@ impl TryFrom<PartialConfig> for Config {
             output_dir: partial_cfg.output_dir.unwrap(),
             n_gen: partial_cfg.n_gen,
             pop_size: partial_cfg.pop_size,
+            delay_const_factor: partial_cfg.delay_const_factor,
         })
     }
 }
@@ -76,7 +89,7 @@ impl TryFrom<Args> for Config {
         let mut partial_cfg = if let Some(ref cfg_file) = args.cfg_file {
             match PartialConfig::try_from(cfg_file.to_owned()) {
                 Ok(cfg) => cfg,
-                Err(err) => return Err(format!("Error while loading config from file: {}", err))
+                Err(err) => return Err(format!("Error while loading config from file: {}", err)),
             }
         } else {
             PartialConfig::empty()
@@ -94,8 +107,10 @@ impl TryFrom<Args> for Config {
         if let Some(pop_size) = args.pop_size {
             partial_cfg.pop_size = Some(pop_size);
         }
+        if let Some(factor) = args.delay_const_factor {
+            partial_cfg.delay_const_factor = Some(factor)
+        }
 
         Config::try_from(partial_cfg)
     }
 }
-

examples/jssp/main.rs

@@ -68,7 +68,7 @@ fn run_with_ecrs(instance: JsspInstance, config: Config) {
         .set_mutation_operator(mutation::Identity::new())
         .set_population_generator(JsspPopProvider::new(instance.clone()))
         .set_replacement_operator(JsspReplacement::new(JsspPopProvider::new(instance), 0.1, 0.2))
-        .set_fitness(JsspFitness::new())
+        .set_fitness(JsspFitness::new(1.5))
         .set_probe(probe)
         // .set_max_duration(std::time::Duration::from_secs(30))
         .set_max_generation_count(n_gen)

examples/jssp/problem/fitness.rs

@@ -14,12 +14,17 @@ pub struct JsspFitness {
     // To put this in other way: all jobs that can be scheduled in time window considered in
     // given iteration g.
     delay_feasibles: Vec<usize>,
+
+    /// The constant used to compute delay for given iteration g. The default value used in paper
+    /// is 1.5.
+    delay_const: f64,
 }
 
 impl JsspFitness {
-    pub fn new() -> Self {
+    pub fn new(delay_constant: f64) -> Self {
         Self {
             delay_feasibles: Vec::new(),
+            delay_const: delay_constant,
         }
     }
 
@@ -131,7 +136,7 @@ impl JsspFitness {
 
     #[inline(always)]
     fn delay_for_g(&self, indv: &JsspIndividual, n: usize, g: usize, maxdur: usize) -> f64 {
-        indv.chromosome[n + g - 1] * 1.5 * (maxdur as f64)
+        indv.chromosome[n + g - 1] * self.delay_const * (maxdur as f64)
     }
 
     #[inline(always)]

examples/jssp/problem/replacement.rs

@@ -35,6 +35,15 @@ impl ReplacementOperator<JsspIndividual> for JsspReplacement {
             population.sort();
         }
 
+        // Divergence from the papaer here. They do sample children population randomly (or just
+        // create just right amount of children).
+        //
+        // This implementation is biased, because children parents are selected from left-to-right
+        // (thus from best to worst) and the offspring is put from left-to-right to the children
+        // arrary & I'm copying here children from left to right ==> only children of better
+        // individuals make it.
+        //
+        // Selection of parents is also done differently to the paper.
         for i in elite_size..(elite_size + crossover_size) {
             std::mem::swap(&mut population[i], &mut children[i - elite_size]);
         }

src/ga/timer.rs

@@ -13,6 +13,8 @@ impl Timer {
     pub(crate) fn start(&mut self) {
         self.start_time = std::time::Instant::now()
     }
+
+    #[inline]
     pub(crate) fn elapsed(&self) -> std::time::Duration {
         self.start_time.elapsed()
     }