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File: main.php
Role: Example script
Content type: text/plain
Description: Example script
Class: PHP Breadth First Search
Find the shortest path to visit warehouse bins
Author: By
Last change:
Date: 5 months ago
Size: 4,562 bytes
 

Contents

Class file image Download
<?php

require_once('params.php');
require_once(
'Graph.php');
require_once(
'PathFinder.php');
require_once(
'Sylvane.php');

/**
 * Returns the unvisited nearest bin.
 *
 * @param string $start
 * The starting point of the bin.
 * @param array $bins
 * The array of subset of the bins.
 * @param array $visited
 * The array of visited bins.
 * @param array $distances
 * The distance between all pairs in the graph.
 * @param array $bin_mapping
 * The associaitve array of mapping bin to the node id.
 */
function getNearestBin($start, $bins, $visited, $distances, $bin_mapping) {

   
// Get the index of the bin in the graph.
   
$start_node_id = $bin_mapping[$start];

   
// Get all the unvisited bins.
   
$unvisited_bins = array_values(array_diff($bins, $visited));

   
// Select the first bin as the nearest.
   
$nearest = $unvisited_bins[0];

   
// Get the index of the nearest bin.
   
$nearest_node_id = $bin_mapping[$nearest];

   
// Get the distance of the bin from the start to the nearest bin.
   
$dist = $distances[$start_node_id][$nearest_node_id];

    for(
$i = 0; $i < count($unvisited_bins); $i++) {

       
// Get the bin at ith index.
       
$bin = $unvisited_bins[$i];

       
// If a shortest distance bin is found then update the nearest bin.
       
if($distances[$start_node_id][$bin_mapping[$bin]] < $dist) {
           
$nearest = $bin;
           
$nearest_node_id = $bin_mapping[$nearest];
           
$dist = $distances[$start_node_id][$nearest_node_id];
        }
    }

    return
$nearest;
}

// Instantiate the graph.
$graph = new Graph ( $num_nodes );

// Setup the graph by adding edges and nodes.
foreach ($edges as $edge) {
   
$graph->addEdge ( $edge[0], $edge[1] );
}

// Get all the bins.
$bins = array_keys( $bin_mapping );
$bins = array_diff( $bins, ['start'] );

// Initialize the Sylvance class object.
$sylvane = new Sylvane( $bins );

// Get 12 random bins.
$random_bins = $sylvane->getRandomBins ( 12 );

// Instantiate the PathFinder class object.
$path_finder = new PathFinder ( $graph );

// Get all distances.
$distances = $path_finder->getDistances();

// Get all paths.
$paths = $path_finder->getPaths();


// Initally no bin is visited.
$visited = [];

// Start from the start position in the warehouse.
$current_node = 'start';

// Store the final path.
$final_path = ['start'];

// Store the path in the graph with node ids.
$exact_path = [14];

while(
count($visited) <= 12) {

    if(
count($visited) < 12) {
       
// Get the nearest bin.
       
$nearest = getNearestBin($current_node, $random_bins, $visited, $distances, $bin_mapping);
    } else {
       
$nearest = 'start';
    }

   
// Mark the nearest bin as visited.
   
$visited[] = $nearest;

   
// Get the path from the current node to the nearest bin.
   
$current_path = $paths[$bin_mapping[$current_node]][$bin_mapping[$nearest]];

   
// Add the path to the exact path.
   
for($i = 1; $i < count($current_path); $i++) {
       
$exact_path[] = $current_path[$i];
    }

   
// Update the current node.
   
$current_node = $nearest;

   
// Add the nearest bin to the final path.
   
$final_path[] = $nearest;
}


echo
"Random Bins selected are:\n---\n";
foreach(
$random_bins as $bin) {
    echo
$bin . "\n";
}

echo
"\n\nThe optimal bin visiting order is as follows:\n---\n";

$i = 0;

foreach(
$final_path as $bin) {
    echo
$bin;

    if(
$i == count($final_path) - 1) {
        echo
"\n";
    } else {
        echo
" -> ";
    }

   
$i++;

}

echo
"\n\nThe exact path in the graph is as follows with a total distance of " . count($exact_path) . " steps:\n---\n";

$i = 0;

foreach(
$exact_path as $node) {
    echo
$node;

    if(
$i == count($exact_path) - 1) {
        echo
"\n";
    } else {
        echo
" -> ";
    }

   
$i++;

}

// Random Bins selected are:
// ---
// B1
// B4
// A6
// A7
// A10
// C1
// C5
// C11
// F2
// F9
// E11
// G5


// The optimal bin visiting order is as follows:
// ---
// start -> C1 -> C5 -> C11 -> E11 -> F9 -> F2 -> B1 -> B4 -> A6 -> A7 -> A10 -> G5 -> start


// The exact path in the graph is as follows with a total distance of 73 steps:
// ---
// 14 -> 15 -> 16 -> 17 -> 18 -> 19 -> 20 -> 21 -> 22 -> 23 -> 24 -> 25 -> 60 -> 61 -> 38 -> 37 -> 36 -> 35 -> 34 -> 33 -> 32 -> 31 -> 30 -> 29 -> 28 -> 27 -> 26 -> 55 -> 54 -> 13 -> 53 -> 52 -> 0 -> 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10 -> 11 -> 12 -> 58 -> 59 -> 25 -> 60 -> 61 -> 38 -> 62 -> 63 -> 51 -> 50 -> 49 -> 48 -> 47 -> 46 -> 45 -> 44 -> 43 -> 42 -> 41 -> 40 -> 39 -> 57 -> 56 -> 26 -> 55 -> 54 -> 13 -> 14