Libchart - Simple PHP chart drawing library

1. How to Create a vertical bar chart

1.1 Create a bar chart object

We first include the chart library in our project, and then create a chart object of dimensions 500 x 250 pixels. If not specified, the image dimensions will be defaulted to sensible values. There are currently 4 types of charts : VerticalBarChart, HorizontalBarChart, LineChart and PieChart.

	include "libchart/libchart.php";

	$chart = new VerticalBarChart(500, 250);

1.2 Create some bars

We add 4 bars to our chart. For that we create a data set and add some bars to it. Each bar is a (label, value) couple, that we call here a Point.

	$dataSet = new XYDataSet();
	$dataSet->addPoint(new Point("Jan 2005", 273));
	$dataSet->addPoint(new Point("Feb 2005", 321));
	$dataSet->addPoint(new Point("March 2005", 442));
	$dataSet->addPoint(new Point("April 2005", 711));

Then we link the data set to the chart:

	$chart->setDataSet($dataSet);

1.3 Display the chart

We set the title and then render the chart to a PNG image.

	$chart->setTitle("Monthly usage for www.example.com");
	$chart->render("generated/demo1.png");

...et voilà!

2. How to create a horizontal bar chart

Creating a horizontal bar chart is similar to the previous example.
Here is the source code and the corresponding result.

	$chart = new HorizontalBarChart(500, 170);

	$dataSet = new XYDataSet();
	$dataSet->addPoint(new Point("/wiki/Instant_messenger", 50));
	$dataSet->addPoint(new Point("/wiki/Web_Browser", 83));
	$dataSet->addPoint(new Point("/wiki/World_Wide_Web", 142));
	$chart->setDataSet($dataSet);

	$chart->setTitle("Most visited pages for www.example.com");
	$chart->render("generated/demo2.png");

3. How to create a pie chart

In order to create a pie chart, we enter 3 points and their associated absolute values. Corresponding percentages are computed automatically.

	$chart = new PieChart(500, 250);

	$dataSet = new XYDataSet();
	$dataSet->addPoint(new Point("Mozilla Firefox (80)", 80));
	$dataSet->addPoint(new Point("Konqueror (75)", 75));
	$dataSet->addPoint(new Point("Other (50)", 50));
	$chart->setDataSet($dataSet);

	$chart->setTitle("User agents for www.example.com");
	$chart->render("generated/demo3.png");

4. How to create a multiple line chart

We already saw how to create a XYDataSet. There is another kind of dataset, XYSeriesDataSet, which allows for several lines/bars concurrently. A XYSeriesDataSet is really a container for several XYDataSet. Here is how it goes:

4.1 Create some series

We create several XYDataSets as earlier.

	include "../libchart/classes/libchart.php";

	$chart = new LineChart(500, 250);

	$serie1 = new XYDataSet();
	$serie1->addPoint(new Point("06-01", 273));
	$serie1->addPoint(new Point("06-02", 421));
	$serie1->addPoint(new Point("06-03", 642));
	$serie1->addPoint(new Point("06-04", 799));
	$serie1->addPoint(new Point("06-05", 1009));
	$serie1->addPoint(new Point("06-06", 1106));
	
	$serie2 = new XYDataSet();
	$serie2->addPoint(new Point("06-01", 280));
	$serie2->addPoint(new Point("06-02", 300));
	$serie2->addPoint(new Point("06-03", 212));
	$serie2->addPoint(new Point("06-04", 542));
	$serie2->addPoint(new Point("06-05", 600));
	$serie2->addPoint(new Point("06-06", 850));

4.2 Create a XYSeriesDataSet

Then we create a XYSeriesDataSet and add our two series to it. Then we link our main data set to the chart.

	$dataSet = new XYSeriesDataSet();
	$dataSet->addSerie("Product 1", $serie1);
	$dataSet->addSerie("Product 2", $serie2);
	$chart->setDataSet($dataSet);

4.3 Render the chart

We render the chart as usual:

	$chart->setTitle("Sales for 2006");
	$chart->render();

You can try out XYSeriesDataSet in conjunction with HorizontalBarChart and VerticalBarChart too!