set colourmap ( rgb<r>:<g>:<b> | hsb<h>:<s>:<b> | cmyk<c>:<m>:<y>:<k> ) [ mask <expr> ]
The setting colourmap is used to specify the mapping between ordinate values and colours used by the colourmap plot style. As elsewhere in PyXPlot, the colour components should be numerical expressions which evaluate to a value in the range zero to one. Within these expressions, the variables c1, c2, c3 and c4 refer quantities calculated from the third through sixth columns of data supplied to the colourmap plot style in a way determined by the c<n>range setting. Thus, the following colour mapping, which is the default, produces a greyscale colour mapping of the third column of data supplied to the colourmap plot style; further columns of data, if supplied, are not used:
set c1range [*:*] renormalise set colourmap rgb(c1):(c1):(c1)
If a mask expression is supplied, then any areas in a colour map where this expression evaluates to zero (i.e. false) are made transparent.