The human eye is incredibly good at recognizing complex behavior and spotting trends and patterns in visually displayed data. If any dataset is larger than about a dozen points, a graph is helpful; if the dataset exceeds a few thousand points, a graph becomes a necessity.
For simple x-y plots, gnuplot is often the first choice. For more complicated problems you can use xmgrace and other plotting tools. However, most simple curve plotters are insufficient for plotting two-dimensional data or for exerting detailed control over a complicated graph. Examples of complicated graphs include specialized bar-and-whiskers plots, time-series with sophisticated error bars, color encodings and density plots, and many other possibilities.
This is where Perl/Tk shines. Chances are, you're already using Perl for data manipulation and extraction. Perl/Tk provides Perl bindings for the Tk GUI toolset and is possibly one of the easiest-to-use widget sets around.
In this article, I'm not as interested in the actual user-interface parts of Perl/Tk (such as checkboxes and drop-down menus) as I am in its graphing capabilities.
Being a GUI-toolkit, Perl/Tk provides an additional facility, which is absent from other graphing extensions to Perl (such as the excellent GD package): namely, the ability for animations and interactive data exploration. I'll show you applications for this in the examples below. |
