how to sync 2 y-axis in Chart director

Question

I have 2 arrays for bar chart. $pm and $estimate.

I am computing $percent = ($estimate / $pm) * 100 to have an array for the percent to create my value for the line chart.

Now the question is how can I sync my 2 y-axis in bar chart and my line chart.

Here's my code

$transmonth = array(1, 2, 3);
$estimate = array(80, 50, 40);
$pm = array(10, 5, 8);

foreach($estimate as $k => $v){
    $percent[$k] = ( $pm[$k] / $v) * 100;
}

$data = $percent;
$data1 = $estimate;
$data2 = $pm;
$labels = $transmonth;

$c = new XYChart(780, 400, -1,1);
$c->addTitle("Mini-PM Hit Rate");

# Set the plotarea at (80, 40) and of 650, 300 pixels in size. Use alternating light
# grey (f8f8f8) / white (ffffff) background. Set border to transparent and use grey
# (CCCCCC) dotted lines as horizontal and vertical grid lines

$c->setPlotArea(80, 80, 650, 250, 0xffffff, 0xf8f8f8,Transparent, $c->dashLineColor(0xcccccc, Dotline), $c->dashLineColor(0xcccccc, Dotline));

$legendObj = $c->addLegend(70, 50, false, "arial.ttf", 10);
$legendObj->setBackground(Transparent);

$lineLayer = $c->addLineLayer2();

$lineLayerObj = $lineLayer->addDataSet($data, 0x009966, "Hit Rate Percentage");
$lineLayerObj->setDataSymbol(CircleShape, 9, 0xff9966, 0x009966);
$lineLayerObj->setDataLabelFormat("{value|1}");
$lineLayerObj->setDataLabelStyle("arialbd.ttf", 8);

$lineLayer->setLineWidth(2);
$lineLayer->setUseYAxis2();
$c->yAxis2->setLinearScale(0, 120, 10);

$layer = $c->addBarLayer2(Side);
$layer->addDataSet($data1, 0x10b4f1, "Estimated PM");
$layer->addDataSet($data2, 0x7B3BA3, "Actual PM");
$layer->setBorderColor(Transparent);
$layer->setBarGap(0.2, TouchBar);


$c->xAxis->setLabels($labels);
$c->xAxis->setTickOffset(0.5);

$c->xAxis->setTitle("Period");
$c->yAxis->setTitle("Total Handlers");
$c->yAxis2->setTitle("Hit Rate Percentage (%)");

header("Content-type: image/png");
print($c->makeChart2(PNG));

Please help.

Answer 1

According to your code, the percentage can be much higher than 100%. However, there is a line in your code configures the yAxis2 to be from 0 to 120 only. So it is possible the percentage data can overflow the axis range. If you remove that line of code and let ChartDirector automatically determine the y-axis scale for yAxis2, the scale will be such that the entire line will fall within the chart.