col_scaler: Color scaling

In raredd/rawr: rawr miscellaneous

Color scaling

Description

Color scaling and interpolation. For a numeric vector and a single color, gradations of transparency is applied corresponding to each numeric value. For two or more, color interpolation is applied.

Usage

col_scaler(
  x,
  colors,
  na.color = NA,
  breaks = NULL,
  alpha = 1,
  alpha.min = min(0.1, x[x >= 0], na.rm = TRUE),
  to = c(0, 1),
  from = range(x, na.rm = TRUE)
)

Arguments

x	a numeric or integer vector
colors	a vector of color names as character strings (or hexadecimal strings) or integers corresponding to colors in the current palette; or a function taking an integer argument that returns a vector of colors (e.g., colorRampPalette or rainbow) if only one color is given, the scaled value of x will determine the amount of transparency; default is from 0 (transparent) to 1 (opaque)
na.color	color used for NA values of x
breaks	(optional) numeric vector to center interpolation; if NULL (default), colors are uniformly spread over a continuous x; useful if colors should be centered at a specific value of x; see examples
alpha	transparency applied to interpolated colors (i.e., if colors is not a single color)
alpha.min	if a single color name is given, sets the lower bound of alpha; a value greater than 0 ensures that the color is visible even for the smallest value of x after rescaling
to, from	output and input range, respectively; see rescaler

Value

A character vector having the same length as x of hexadecimal color values.

Examples

## basic usage
col_scaler(mtcars$mpg, 'red')
col_scaler(mtcars$vs, c('red', 'black'))


set.seed(1)
x <- sort(runif(50, 0, 2))
# x <- replace(x, runif(length(x)) > 0.75, NA)
p <- function(y, c) {
  points(seq_along(c), rep_len(y, length(c)),
         col = c, pch = 16, cex = 5, xpd = NA)
}

plot.new()
plot.window(c(0, 50), c(-3, 3))
p( 4, col_scaler(x, 'red'))
p( 3, col_scaler(x, c('red', 'blue')))
p( 2, col_scaler(x, c('red', 'blue'), to = c(.4, .8)))
p( 1, col_scaler(round(x), c('red', 'blue'), alpha = 0.5))
p( 0, col_scaler(x, 1:10))
p(-1, col_scaler(round(x), 1:3))
p(-2, col_scaler(x, 'heat.colors'))
p(-3, col_scaler(x, rainbow, alpha = 0.1))
p(-4, col_scaler(x, colorRampPalette(c('tomato', 'white', 'blue4'))))


set.seed(1)
x <- runif(1000)
y <- c('red', 'black', 'red')
op <- par(mfrow = c(2, 2), mar = c(3, 3, 1, 1))
plot(x, col = col_scaler(x, y), pch = 16)
plot(x, col = col_scaler(x, y, breaks = 0.5), pch = 16)
plot(x, col = col_scaler(x, y, breaks = 0.9), pch = 16)
plot(x, col = col_scaler(x, c(y, 'blue'), breaks = c(0.25, 0.75)), pch = 16)
par(op)

raredd/rawr documentation built on March 4, 2024, 1:36 a.m.