Class: Railbow::ColorAssigner

Inherits:
Object
  • Object
show all
Defined in:
lib/railbow/color_assigner.rb

Overview

Assigns maximally-spaced colors to a set of unique labels.

Instead of hashing into a fixed palette (where two labels can collide onto adjacent colors), this assigns colors by rank — evenly spacing hues around the color wheel. Two labels always get maximally different colors, three labels get ~120 deg apart, etc.

Usage:

assigner = Railbow::ColorAssigner.new(["Alice", "Bob", "Carol"])
assigner.color_for("Alice")  # => "\e[38;5;174m"
assigner.code_for("Bob")     # => 116  (256-color code)

Constant Summary collapse

WHEEL =

Soft/muted 256-color codes arranged around the hue wheel. 12 stops, evenly spaced in hue, all at moderate saturation/lightness so they look pleasant on dark terminals.

[
  174, # 0°   coral / muted rose
  216, # 30°  peach
  180, # 60°  warm sand
  150, # 120° sage green
  116, # 160° soft teal
  117, # 200° soft sky blue
  111, # 220° periwinkle
  146, # 260° lavender
  176, # 300° soft magenta
  182  # 330° dusty pink
].freeze

Instance Method Summary collapse

Constructor Details

#initialize(labels) ⇒ ColorAssigner

Returns a new instance of ColorAssigner.



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# File 'lib/railbow/color_assigner.rb', line 33

def initialize(labels)
  sorted = labels.uniq.sort
  @mapping = {}
  sorted.each_with_index do |label, idx|
    wheel_idx = (idx * WHEEL.size / [sorted.size, 1].max) % WHEEL.size
    @mapping[label] = WHEEL[wheel_idx]
  end
end

Instance Method Details

#code_for(label) ⇒ Object

Returns just the 256-color code integer for the given label.



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# File 'lib/railbow/color_assigner.rb', line 49

def code_for(label)
  @mapping[label] || WHEEL[0]
end

#color_for(label) ⇒ Object

Returns the 256-color ANSI escape for the given label.



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# File 'lib/railbow/color_assigner.rb', line 43

def color_for(label)
  code = code_for(label)
  "\e[38;5;#{code}m"
end