This helper class will find the closest hex color from an array of hex colors

hex_color.rb

# By: Ryan Marshall
#
# This helper class will find the closes hex color from an array of other hex colors
# 
#
# colors = ["e00928","24519b","461b00", "dae12a", "ff9c3e",]
# color = "285fa2"
#

class HexColor
  
  #
  # Will match the closest hex color from an array of hex colors
  #
  def self.closest(color, colors)
    difference = get_difference_array(color, colors)
    index = difference.index( difference.min )
    colors[index]
  end

  def self.get_difference_array(color, colors)
    difference = []
    colors.each do |c|
      color_rgb = self.hex2rgb(color)
      base_rgb  = self.hex2rgb(c)

      number =
      ( color_rgb[:red] - base_rgb[:red] ) * 
      ( color_rgb[:red] - base_rgb[:red] ) + 
      ( color_rgb[:green] - base_rgb[:green] ) * 
      ( color_rgb[:green] - base_rgb[:green] ) + 
      ( color_rgb[:blue] - base_rgb[:blue] ) * 
      ( color_rgb[:blue] - base_rgb[:blue] )
      difference << Math.sqrt(number)
    end
    difference
  end

  def self.hex2rgb(color)
    r = Integer(color[0..1], 16)
    g = Integer(color[2..3], 16)
    b = Integer(color[4..5], 16)
    {
      red: r,
      green: g,
      blue: b,
    }
  end
  
end