Gnuplot is a general-purpose plotting package driven from the command line or from a scripted environment like a web server. It is one of the oldest open source projects around, having been in continuous development since its first release in 1987. This week gnuplot released a sixth and, according to the developers, probably final incremental update to the version 4.2 release series.
In addition to stand-alone use, gnuplot serves as the graphics output layer for other open source data visualization tools such as Octave and Gretl. It supports a huge variety of output modes, from ancient pen plotters to recent TeX variants like TikZ, from character cell terminals to recently added output modes using the Qt and WxWidgets toolkits. Another recent addition is the ability to draw graphs into the HTML5 canvas element, which can be embedding on web pages to offer client-side mouse tracking and zoom. For an idea of its capabilities, check out the project’s collection of demo plots.
Developer Ethan Merritt says, “We’ve been managing to put out a minor release every six months or so, with two or three years of development between major releases. The development version containing the latest features under development is always available by CVS, and is generally rock solid. Next up is a first release candidate for a major jump to version 4.4, which adds a ton of new features we’ve developed over the past two years. Version 4.4 introduces new plot styles, support for alpha-blend compositing, new output modes and terminal types, internationalization, and extensions to the command syntax for more flexible scripting.”
Merritt says many new features are inspired by specific requests from users who need to make a particular kind of plot for publication or internal use, but can’t find a way to do it. The project welcomes anyone who uses either 2-D or 3-D plots for data visualization to tell them in what way what they want to do isn’t yet possible.
Gnuplot has opportunities for developers who want to work on the code. Merritt says, “Our biggest shortage right now is developers interested in troubleshooting and fixing bugs specific to the Windows GUI. At the moment it’s lagging the capabilities of newer output modes that using cairo/pango, Qt, or WxWidgets for better font handling and smoother graphics. Of course you can in principle use these newer toolkits under Windows also, but there are still a lot of people used to the old Windows interactive GUI.”