heplots (version 1.6.2)

trans.colors: Make Colors Transparent

Description

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)

Value

A vector of color values of the form "#rrggbbaa"

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

Author

Michael Friendly

Details

Colors (col) and alpha need not be of the same length. The shorter one is replicated to make them of the same length.

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=""))