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Find the R built-in colour that's closest in RGB space to a given colour
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# Find the R built-in colour that's closest in RGB space to a given colour | |
# This can be useful if you have a colour in mind you want to use in your R | |
# code, but would rather use a pretty built-in name rather than a HEX value. | |
# | |
# @param target The target RGB colour, given as a length-3 numeric vector | |
# @param n The number of top hits to return | |
# @param superset A vector with all possible colour names to choose from | |
# | |
# Note that the closest colour in RGB space is not guaranteed to be the | |
# closest colour visually, but it works in many cases. | |
# | |
# @examples | |
# closest_colour(c(100, 100, 100)) -> "gray39" | |
# closest_colour(c(0, 230, 0), 3) -> "green2" "green" "green1" | |
# closest_colour(c(240, 150, 30)) -> "goldenrod2" | |
# closest_colour(col2rgb("red"), 3) -> "red" "red1" "red2" | |
library(magrittr) | |
closest_colour <- function(target, n = 1, superset = colours()) { | |
target %<>% as.numeric | |
# Find the manhattan distance from each colour to the target colour | |
superset %>% | |
col2rgb %>% | |
subtract(target) %>% | |
apply(2, function(x) x %>% abs %>% sum) %>% | |
order %>% | |
.[1:n] %>% | |
superset[.] | |
} | |
# This version takes HEX colours instead of RGB vectors, and can | |
# deal with multiple colour inputs. | |
# @examples | |
# closest_colour_hex(c("#ff0010", "#f1f1f1")) -> c("red", "gray94") | |
closest_colour_hex <- function(targets, n = 1, superset = colours()) { | |
vapply(targets, function(target) { | |
target <- target %>% col2rgb %>% as.numeric | |
# Find the manhattan distance from each colour to the target colour | |
superset %>% | |
col2rgb %>% | |
subtract(target) %>% | |
apply(2, function(x) x %>% abs %>% sum) %>% | |
order %>% | |
.[1:n] %>% | |
superset[.] | |
}, character(n)) | |
} |
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Very useful, thanks!