l_colorName: Get Color Names from the Hex Code

Description

Return the built-in color names by the given hex code.

Usage

l_colorName(color, error = TRUE, precise = FALSE)

Value

A vector of built-in color names

Arguments

color: A vector of 12 digit (tcl) or 6 (8 with transparency) digit color hex code, e.g. "#FFFF00000000", "#FF0000"
error: Suppose the input is not a valid color, if TRUE, an error will be returned; else the input vector will be returned.
precise: Logical; When precise = FALSE, the name of the nearest built-in colour is returned. When precise = TRUE, the name is returned only if the minimum Euclidean distance is zero; otherwise the hex code of the colour is returned. See details.

Details

Function colors returns the built-in color names which R knows about. To convert a hex code to a real color name, we first convert these built-in colours and the hex code to RGB (red/green/blue) values (e.g., "black" --> [0, 0, 0]). Then, using this RGB vector value, the closest (Euclidean distance) built-in colour is determined.

Matching is "precise" whenever the minimum distance is zero; otherwise it is "approximate", locating the nearest R colour.

Examples

Run this code

l_colorName(c("#FFFF00000000", "#FF00FF", "blue"))

if(require(grid)) {
# redGradient is a matrix of 20 different colors
redGradient <- matrix(hcl(0, 80, seq(49, 68, 1)),
                      nrow=4, ncol=5, byrow = TRUE)
# a color plate
grid::grid.newpage()
grid::grid.raster(redGradient,
                  interpolate = FALSE)

# a "rough matching";
r <- l_colorName(redGradient)
# the color name of each row is identical...
r
grid::grid.newpage()
# very different from the first plate
grid::grid.raster(r, interpolate = FALSE)

# a "precise matching";
p <- l_colorName(redGradient, precise = TRUE)
# no built-in color names can be precisely matched...
p
}
if (FALSE) {
# an error will be returned
l_colorName(c("foo", "bar", "red"))

# c("foo", "bar", "red") will be returned
l_colorName(c("foo", "bar", "#FFFF00000000"), error = FALSE)
}