source: trunk/xgraph/jpgraph/Examples/windrose_ex3.php

<?php
require_once ('jpgraph/jpgraph.php');
require_once ('jpgraph/jpgraph_windrose.php');

// Data can be specified using both ordinal index of the axis
// as well as the direction label
$data[0] = array(
    0 => array(1,1,2.5,4),
    1 => array(3,4,1,4),
    3 => array(2,7,4,4,3),
    5 => array(2,7,1,2));

$data[1] = array(
    "n" => array(1,1,2.5,4),
    "ssw" => array(3,4,1,4),
    "se" => array(2,7,4,4,3));

// Store the position and size data for each plot in an
// array to make it easier to create multiple plots.
// The format choosen for the layout data is
// (type,x-pos,y-pos,size, z-circle size)
$layout = array(
    array(WINDROSE_TYPE8,0.25,0.55,0.4,0.25),
    array(WINDROSE_TYPE16,0.75,0.55,0.4,0.25));

$legendtxt = array('(m/s) Station 7','(m/s) Station 12');

// First create a new windrose graph with a dropshadow
$graph = new WindroseGraph(600,350);
$graph->SetShadow('darkgray');

// Setup titles
$graph->title->Set('Windrose example 3');
$graph->title->SetFont(FF_VERDANA,FS_BOLD,12);
$graph->title->SetColor('navy');
$graph->subtitle->Set('(Multiple plots in the same graph)');
$graph->subtitle->SetFont(FF_VERDANA,FS_NORMAL,9);
$graph->subtitle->SetColor('navy');

// Create the two windrose plots.
for( $i=0; $i < count($data); ++$i ) {
    $wp[$i] = new WindrosePlot($data[$i]);

    // Make it have 8 compass direction
    $wp[$i]->SetType($layout[$i][0]);

    // Adjust the font and font color for scale labels
    $wp[$i]->scale->SetFont(FF_TIMES,FS_NORMAL,10);
    $wp[$i]->scale->SetFontColor('navy');

    // Set the position of the plot
    $wp[$i]->SetPos($layout[$i][1],$layout[$i][2]);

    // Set the diameter for the plot to 30% of the width of the graph pixels
    $wp[$i]->SetSize($layout[$i][3]);

    // Set the size of the innermost center circle to 30% of the plot size
    $wp[$i]->SetZCircleSize($layout[$i][4]);

    // Adjust the font and font color for compass directions
    $wp[$i]->SetFont(FF_ARIAL,FS_NORMAL,10);
    $wp[$i]->SetFontColor('darkgreen');

    // Add legend text
    $wp[$i]->legend->SetText($legendtxt[$i]);

    $graph->Add($wp[$i]);
}

// Send the graph to the browser
$graph->Stroke();
?>