Create a calibrated color ramp object from color-tiepoint data.frames

Create ramp palettes from fixed color positions.

Usage

expand(x = NULL, n, color = "color", z = "z", ...)

Arguments

x: A data.frame object with two columns: color for hexadecimal color values, z for their position.
n: A single integer number.
color: A chraracter value, the column name of the colors in x, defaults to "color". Alternatively, a character vector of hexadecimal color values, with the same length as z.
z: A character value, the column name of the values in x, defaults to "z". Alternatively, a numeric vector of color values (must have the same length as color.
...: Arguments passed to the colorRampPalette function.

Value

A calibramp-class object (see description above).

Details

The function creates objects of the S3 class calibramp. The calibramp-class lists have three elements: col hexadecimal color values, mid: z-values of midpoints (one for every color), and breaks: separator borders between color values. Color interpolation will be executed linearly, using colorRampPalette, the order of the values will be forced to ascending, the values in mid will be halfway between breaks.

Examples

library(rampage)
data(topos)
ramp <- expand(topos$havanna2, n=200)
plot(ramp)