Triangular Plot

Triangular plot is a barycentric plot on three variables which sum to a constant. It graphically depicts the ratios of the three variables as positions in an equilateral triangle. It is used in petrology, mineralogy, metallurgy, and other physical sciences to show the compositions of systems composed of three species. In population genetics, it is often called a de Finetti diagram. In game theory, it is often called a simplex plot. The axes of the figure show the estimated fraction of the United Kingdom population intending to vote for each of the major parties; the white circle shows the current estimate from opinion polls. The colored 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.