Triangular Plot

Triangular plot of current election in the United Kingdom

The axes of the figure show the estimated fraction of the population intending to vote for each of the major parties; the white circle shows the current estimate from opinion polls. The coloured areas show the regions of the plot in which -- under the assumption of uniform national swing each of the corresponding major parties would win a majority in Parliament.

A triangle plot also known as a ternary plot, is a graph of 3 variables. It is most often used in geologic studies to show the relative compositions of soils and rocks, but it can be more generally applied to any system of three variables.

http://ex-parrot.com/~chris/images/20050407/triangle.png