addAlpha: Color transparency

In berryFunctions: Function Collection Related to Plotting and Hydrology

Color transparency

Description

Make existing colors semi-transparent (add alpha)

Usage

addAlpha(col, alpha = 0.3)

Arguments

col	Vector of color names (colors), hexadecimal or integer that can be interpreted by col2rgb
alpha	Level of semi-transparency. between 0 (transparent) and 1 (intransparent). Can also be a vector. DEFAULT: 0.3

Value

character vector with hexadecimal color codes.

Author(s)

Berry Boessenkool, [e-mail], June 2014 Based on suggestion by Mathias Seibert, Dec. 2013

See Also

addFade, rgb, colors, col2rgb

Examples

addAlpha("red", c(0.1, 0.3, 0.6, 1))
addAlpha(1:3)
addAlpha(1:3, 1:3/3)
NewColors <- addAlpha(c("red","blue","yellow","green", "purple"), 0:200/200)
plot(runif(1000), col=NewColors, pch=16, cex=2)

# use addFade for line segments, because of overlapping dots
set.seed(1); x <- cumsum(rnorm(30))  ; y <- x-2
plot(x, type="n")
segments(x0=1:29,y0=head(x,-1), x1=2:30,y1=x[-1], col=addAlpha(4, 29:0/30), lwd=10)
segments(x0=1:29,y0=head(y,-1), x1=2:30,y1=y[-1], col=addFade (4, 29:0/30), lwd=10)

berryFunctions documentation built on May 29, 2024, 4:01 a.m.