color distance

distance.R

library(dplyr)

n <- 1000000
data <- data.frame(id = 1:n,
                   red = sample(0:255, size = n, replace = TRUE),
                   green = sample(0:255, size = n, replace = TRUE),
                   blue = sample(255, size = n, replace = TRUE))

query <- list(red = 80, green = 90, blue = 255)
                             
results <- data %>%
  mutate(eu_dist = sqrt((red - query$red)^2 + 
                  (blue - query$blue)^2 +
                  (green - query$green)^2)) %>%
  arrange(eu_dist)

print(head(results))

# output
# > print(head(results))
#      id red green blue  eu_dist
# 1 850076  81    91  255 1.414214
# 2 245256  81    88  255 2.236068
# 3 255701  79    89  253 2.449490
# 4 864183  78    89  254 2.449490
# 5 126499  78    90  253 2.828427
# 6 904071  79    90  252 3.162278