source: trunk/xgraph/jpgraph/Examples/y2synch2.php @ 42

<?php // content="text/plain; charset=utf-8"
require_once ('jpgraph/jpgraph.php');
require_once ('jpgraph/jpgraph_line.php');
require_once ('jpgraph/jpgraph_bar.php');


function toFahrenheit($aVal) {
    return round(($aVal*9/5)+32,2);
}

function toCelcius($aVal) {
    return round(($aVal-32)*5/9,2);
}


$datay =array(2,3,8,19,7,17,6,22);

// Create the graph. 
$graph = new Graph(400,280);

// Slightly bigger margins than default to make room for titles
$graph->SetMargin(50,60,40,45);
$graph->SetMarginColor('white');


// Setup the scales for X,Y and Y2 axis
$graph->SetScale("textlin"); // X and Y axis
$graph->SetY2Scale("lin"); // Y2 axis

// Overall graph title
$graph->title->Set('Synchronized Y & Y2 scales');
$graph->title->SetFont(FF_ARIAL,FS_BOLD,12);

// Title for X-axis
$graph->xaxis->title->Set('Measurement');
$graph->xaxis->title->SetMargin(5);
$graph->xaxis->title->SetFont(FF_ARIAL,FS_NORMAL,11);

// Create Y data set 
$lplot = new BarPlot($datay);
$graph->yaxis->title->Set('Celcius (C)');
$graph->yaxis->title->SetMargin(5);
$graph->yaxis->title->SetFont(FF_ARIAL,FS_NORMAL,11);
// ... and add the plot to the Y-axis
$graph->Add($lplot);

// Create Y2 scale data set 
$l2plot = new LinePlot($datay);
$l2plot->SetWeight(0);
$graph->y2axis->title->Set('Fahrenheit (F)');
$graph->y2axis->title->SetMargin(5); // Some extra margin to clear labels
$graph->y2axis->title->SetFont(FF_ARIAL,FS_NORMAL,11);
$graph->y2axis->SetLabelFormatCallback('toFahrenheit');
$graph->y2axis->SetColor('navy');

// ... and add the plot to the Y2-axis
$graph->AddY2($l2plot);

$graph->Stroke();
?>