<?php

# PHPlot Example - Box Plot (without outliers)

require_once 'phplot.php';

# The experimental results:

$results = array(

'Material A1' =>

array(11.1, 8.4, 11.9, 13, 10.2, 9.2),

'Material A2' =>

array(10.6, 9.8, 9.1, 12, 8.5, 7.1, 8.2, 7.8, 11.8),

'Material B1' =>

array(9.9, 11.2, 10.9, 12.9, 8.5),

'Material C1' =>

array(10.1, 11.8, 11.6, 8.5, 9.6, 12, 12, 8.9, 12.7, 10.3, 11.1),

'Material C2' =>

array(10.9, 11.9, 7.3, 11.7, 12.6, 9.2, 10, 7, 7.1),

'Material C3' =>

array(11.9, 9.1, 10.5, 10.7, 10, 7.3, 10.1, 11.7, 10.4, 9),

'Material D1' =>

array(12, 8, 9.8, 11.4, 10.5, 12.5, 7.1, 8.6, 7.6, 7.4, 8.2, 7.1),

'Material E1' =>

array(10.6, 8.2, 8.2, 7.9, 12, 7, 9.3),

);

# Return the k-th percentile value of a sorted array, where 0 <= $k <= 1

# If there is no single value, return the average of the two adjacent ones.

# Caution: Don't copy this code. It may not be valid, but suits the example.

function kpercentile($row, $k)

{

$n = count($row);

$p = $k * ($n - 1);

if ($p == (int)($p)) return $row[$p];

return ($row[(int)$p] + $row[(int)($p+1)]) / 2;

}

# Convert the experimental results to a PHPlot data array.

function reduce_data($results)

{

$data = array();

foreach ($results as $label => $row) {

$n_samples = count($row);

sort($row);

$data[] = array("$label\n($n_samples Samples)",

$row[0], // Minimum

kpercentile($row, 0.25), // Q1 = 25%

kpercentile($row, 0.50), // Median

kpercentile($row, 0.75), // Q3 = 75%

$row[$n_samples-1]); // Maximum

}

return $data;

}

$plot = new phplot(800, 600);

$plot->SetTitle('Box Plot (without outliers)');

$plot->SetDataType('text-data');

$plot->SetDataValues(reduce_data($results));

$plot->SetPlotType('boxes');

# These 2 lines make tick marks line up with text-data data points:

$plot->SetXTickIncrement(1);

$plot->SetXTickAnchor(0.5);

$plot->SetImageBorderType('plain'); // Improves presentation in the manual

$plot->DrawGraph();