SVGGraph 2.19
Published
The main change in version 2.19 of SVGGraph is the addition of a Histogram graph type. I haven't considered adding one until now because I figured people could work out how to do it for themselves and use one of the existing bar graph classes. I've changed my mind - histograms actually work quite differently to bar graphs, so I've produced these two graphs to demonstrate the difference.
The example above is a standard BarGraph displaying the current sizes of the
PHP files in the SVGGraph library. There are a couple of fairly large files and
quite a few smaller files. I've used a simple associative array to pass the file
sizes to SVGGraph. (The actual values might have changed a bit since I generated
them using ls and awk.)
$values = array(
"SVGGraph.php" => 53849,
"SVGGraph3DGraph.php" => 8037,
...
);
$graph->Values($values);
The graph below is a Histogram of the same values. For this graph, SVGGraph
counts the values, groups them into ranges and draws bars that show how many
occurrences of the values there are in each range. SVGGraph will pick the ranges
automatically, or you can specify your own size for the ranges with the
increment option.
The number on the Y axis of the histogram is the number of occurrences - the
Histogram class also supports displaying the results as a percentage (by setting
the percentage option to true).
These graphs also demonstrate the axis_text_callback_x and
axis_text_callback_y options introduced in version 2.18, and the
new tooltip_callback option added in this version. The axis callbacks
are used to convert plain integers into file sizes, and the tooltip callback
turns the text into a more readable format. There is also a new callback for
labels, data_label_callback, which works in the same way as the
tooltip callback, taking the dataset number, key and value as arguments.
Other new options not demonstrated here are best_fit_opacity and
best_fit_above for more control over the scatter graph best-fit
lines, data_label_min_space for hiding labels for tiny bars or pie
slices, and several new options for shading the top, side and front of the 3D
bars to give them more depth. Those are covered in a new section on the
3D bar graphs page.
Apart from all that, this is the first version that I am going to make available for automatic installation using Composer. If you're not aware of it, Composer helps you manage the libraries that you are using in your PHP application. I've already made a couple of alpha and beta versions available for those who like to live on the edge (and to help me test that I've got it working right).
The new version is available from the downloads page, or from GitHub, or using Composer.