Matching colors across palettes

Sometimes a palette or particular colours are chosen to symbolise or represent a particular idea, such as red for "stop" or green for "go", or to convey some other interpretation. Yet institutional palettes do not necessarily include all colours, which can constrain how interpretable visualisations are under institutional branding requirements. match_color() helps to find the closest matching colours in a given palette to one or more input colours.

There is also a helper function, is_dark(), to determine whether a color is dark or light, which can be useful when deciding whether to use white or black text on top of a colored background.

Usage

match_color(colors, pal)

is_dark(colors)

Arguments

colors

One or more hexcodes to match with colors from the palette.

pal

Optionally, a vector of hexcodes representing a palette in which to find matches. By default, the current theme's qualitative palette is used.

Value

A vector of hexcodes the length of the first argument.

Details

This function uses the Euclidean distance of colours in CIELAB space to those of a target palette to find the closes corresponding colours. It also ensures that each input color is matched to a unique color in the palette. If there are more input colors than unique colors in the palette, an error is returned.

By default, the current theme's qualitative palette is used, but any vector of hexcodes can be passed to the pal argument.

Examples

match_color("#4575b4")
#> [1] "#4575B4"
is_dark(c("#000","#FFF"))
#>  #000  #FFF 
#>  TRUE FALSE