Takes a vector of colors (as color names or rgb hex values) and adds a specified
alpha transparency to each.
Usage
trans.colors(col, alpha = 0.5, names = NULL)
Arguments
col
A character vector of colors, either as color names or rgb hex values
alpha
alpha transparency value(s) to apply to each color (0 means fully transparent and 1 means opaque)
names
optional character vector of names for the colors
Details
Colors (col) and alpha need not be of the same length.
The shorter one is replicated to make them of the same length.
Value
A vector of color values of the form "#rrggbbaa"
Author(s)
Michael Friendly
See Also
col2rgb,
rgb, adjustcolor,
Examples
trans.colors(palette(), alpha=0.5)
# alpha can be vectorized
trans.colors(palette(), alpha=seq(0, 1, length=length(palette())))
# lengths need not match: shorter one is repeated as necessary
trans.colors(palette(), alpha=c(.1, .2))
trans.colors(colors()[1:20])
# single color, with various alphas
trans.colors("red", alpha=seq(0,1, length=5))
# assign names
trans.colors("red", alpha=seq(0,1, length=5), names=paste("red", 1:5, sep=""))