This first script shows the default behavior - percentage labels.

<?php
# PHPlot Example: Pie Chart Label Types - baseline, default label type
# This requires PHPlot >= 5.6.0
require_once 'phplot.php';
require_once 'pielabeltypedata.php'; // Defines $data and $title

$plot = new PHPlot(800, 600);
$plot->SetImageBorderType('plain'); // Improves presentation in the manual
$plot->SetPlotType('pie');
$plot->SetDataType('text-data-single');
$plot->SetDataValues($data);
$plot->SetTitle($title);
$plot->DrawGraph();

The example below uses the label strings from the data array to label the pie segments. Note that this only works when the data array data type is text-data-single.

<?php
# PHPlot Example: Pie Chart Label Types - Labels from data array
# This requires PHPlot >= 5.6.0
require_once 'phplot.php';
require_once 'pielabeltypedata.php'; // Defines $data and $title

$plot = new PHPlot(800, 600);
$plot->SetImageBorderType('plain'); // Improves presentation in the manual
$plot->SetPlotType('pie');
$plot->SetDataType('text-data-single');
$plot->SetDataValues($data);
$plot->SetTitle($title);
# Set label type: Use labels from data array
$plot->SetPieLabelType('label');
$plot->DrawGraph();

The next example uses the numeric value of each segment to label the segment. In addition, 'data' formatting is used with 2 digits of precision.

<?php
# PHPlot Example: Pie Chart Label Types - Formatted values as labels
# This requires PHPlot >= 5.6.0
require_once 'phplot.php';
require_once 'pielabeltypedata.php'; // Defines $data and $title

$plot = new PHPlot(800, 600);
$plot->SetImageBorderType('plain'); // Improves presentation in the manual
$plot->SetPlotType('pie');
$plot->SetDataType('text-data-single');
$plot->SetDataValues($data);
$plot->SetTitle($title);
# Set label type: segment values, formatted with 2 decimal places
$plot->SetPieLabelType('value', 'data', 2);
$plot->DrawGraph();

In this example, we want to use strings from an external array to label the pie segments. To do that, set the label source to 'index' to get a segment number starting with zero, and define a custom formatting callback function to get the value for each label.

<?php
# PHPlot Example: Pie Chart Label Types - Index and custom callback
# This requires PHPlot >= 5.6.0
require_once 'phplot.php';
require_once 'pielabeltypedata.php'; // Defines $data and $title

$mylabels = array('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J');
function mycallback($index)
{
    global $mylabels;
    return $mylabels[$index];
}

$plot = new PHPlot(800, 600);
$plot->SetImageBorderType('plain'); // Improves presentation in the manual
$plot->SetPlotType('pie');
$plot->SetDataType('text-data-single');
$plot->SetDataValues($data);
$plot->SetTitle($title);
# Set label type: Pass segment index (0-N) to custom formating function
$plot->SetPieLabelType('index', 'custom', 'mycallback');
$plot->DrawGraph();

The last example of pie chart labels shows how to use multiple label sources to make complex labels. In this case, we want the pie segment labels to show the label string from the data array and the percentage. When multiple label sources are selected, PHPlot separates the fields with a space, then passes them to your custom formatting callback function as a single string. In order to separate them, use the explode(). Since the data array labels might contain spaces, be sure to put this field last, and limit how many fields explode will return.

<?php
# PHPlot Example: Pie Chart Label Types - Multi-part labels
# This requires PHPlot >= 5.6.0
require_once 'phplot.php';
require_once 'pielabeltypedata.php'; // Defines $data and $title

function mycallback($str)
{
    list($percent, $label) = explode(' ', $str, 2);
    return sprintf('%s (%.1f%%)', $label, $percent);
}

$plot = new PHPlot(800, 600);
$plot->SetImageBorderType('plain'); // Improves presentation in the manual
$plot->SetPlotType('pie');
$plot->SetDataType('text-data-single');
$plot->SetDataValues($data);
$plot->SetTitle($title);
# Set label type: combine 2 fields and pass to custom formatting function
$plot->SetPieLabelType(array('percent', 'label'), 'custom', 'mycallback');
$plot->DrawGraph();