The GraPL Engine – History and Heritage

1989 - where it all started

The motivation for the original graphing engine (called “Rain” for reasons you will shortly see) was very simple: we had recently moved to the country and were recording daily max-min temperatures and rainfall just for our own interest. I wanted to plot these readings on a chart that gave me a simple, clear graphical picture of the data. I had also just read Tufte's marvellous “The Visual Display of Quantitative Information” (Graphics Press, 1983) and I was determined to follow his lead in combining typographical excellence with clear presentation of data.

As you might expect, there was nothing I could buy which came close. A simple (to me obvious) requirement was to have monthly tickmarks on my X-axis, but of course months have different numbers of days! I wanted tickmarks at 0,31,(31+28) ... ,365 rather than at equal intervals. Something like this, in fact:

OK, at this size you might think it doesn't matter, but on a 600dpi printer there are over 14 dots on the paper for each day of the year (printed Landscape) so you really can plot the rain for each day as a vertical spike. Here is part of the same chart, zoomed up so that you can see it:

Now I hope you can see that February really is a short month. It is also instructive to see just how much of a month's rain typically falls on only one or two days, even in the damp, temperate lowlands of the UK. The technology I had available to me was mostly DOS-based, but included an HP DeskJet printer and a package called GoScript which will take a PostScript file and 'render' it on all sorts of simple devices, such as DeskJets. Time to stop wanting and start designing.