color.with.alpha: Color Opacity

In ArcadeAntics/essentials: Essential Functions not Included in Base R

Color Opacity

Description

Change the alpha (opacity) of a series of colors.

Usage

color.with.alpha(x, alpha)
as.hex.code(x)

Arguments

x	character vector, a matrix as produced by col2rgb, or a matrix or data.frame where the first three columns are the red, green, and blue values.
alpha	an alpha-transparency level in the range [0,1] (0 means transparent and 1 means opaque).

Details

When alpha is missing, the alpha-transparency is taken from x. In that case, color.with.alpha is just decoding the colors into a character vector of hex colors codes, and not actually changing the opacity of the colors.

Value

A character vector of hex color codes.

Examples

example.colors <- c("red", "#FFA50099", "yellow", "green", "blue", "purple")
show.colors(example.colors)
show.colors(color.with.alpha(example.colors, alpha = NULL))  # remove all opacity
show.colors(color.with.alpha(example.colors, alpha = 0.25))  # one quarter opaque
show.colors(color.with.alpha(example.colors, alpha = 0.5))   # half opaque
show.colors(color.with.alpha(example.colors, alpha = 0.75))  # three quarters opaque
show.colors(color.with.alpha(example.colors, alpha = 1))     # fully opaque, same as NULL


example.colors2 <- 1:8
show.colors(example.colors2)
show.colors(color.with.alpha(example.colors2, alpha = 0.5))
show.colors(color.with.alpha(example.colors2, alpha = 0.75))


example.colors3 <- grDevices::col2rgb(gg.colors(10))


## show.colors would not be able to show example.colors3 because it's a matrix
## use as.hex.codes to decode the values to their hex codes, then display
show.colors(as.hex.code(example.colors3))
show.colors(color.with.alpha(example.colors3, alpha = 0.5))
show.colors(color.with.alpha(example.colors3, alpha = 0.75))


example.colors4 <- data.frame(
    red   = c( 75,  66,  24,   0,   0,   0,   0, 108, 187, 253)/255,
    green = c(  0,  44,  80, 112, 142, 168, 190, 208, 221, 227)/255,
    blue  = c( 85, 112, 134, 148, 152, 144, 125,  94,  56,  51)/255
)
show.colors(as.hex.code(example.colors4))
show.colors(color.with.alpha(example.colors4, alpha = 0.5))
show.colors(color.with.alpha(example.colors4, alpha = 0.75))

# alpha can be a vector, here we provide 10 different alpha values
show.colors(color.with.alpha(example.colors4,
    alpha = seq.int(0.5, 1, length.out = 10)))

ArcadeAntics/essentials documentation built on Nov. 7, 2024, 4:33 p.m.