<?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\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("intlin"); // 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
$lplot = new Plot\LinePlot($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
$l2plot = new Plot\LinePlot($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();
