Add an Alpha Channel to Colors

Add transparency to colors.

Usage

addOpacity(col, opacity = 0.5)

Arguments

col

vector of valid R colors

opacity

opacity value between 0 and 1

Value

Character vector of hexadecimal colors with alpha channel.

See also

grDevices::adjustcolor

Other color.manipulation: colToOpaque(), darken(), fade(), lighten(), mixColors()

Examples

op <- par(no.readonly = TRUE)

addOpacity("yellow", 0.2)
#>      yellow 
#> "#FFFF0033" 
addOpacity(2, 0.5)   # red
#> [1] "#DF536B80"

canvas(3)
polygon(circle(x=c(-1,0,1), y=c(1,-1,1), radius=2), 
        col=addOpacity(2:4, 0.4))


x <- rnorm(15000)
par(mfrow=c(1,2))
plot(x, type="p", col="blue" )
plot(x, type="p", col=addOpacity("blue", .2), 
     main="Better insight with alpha channel" )


par(op)