Module: Math

Included in:
Paleta::Color, Paleta::Palette
Defined in:
lib/paleta/core_ext/math.rb

Instance Method Summary collapse

Instance Method Details

#distance(a, b) ⇒ Object 



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# File 'lib/paleta/core_ext/math.rb', line 2

def distance(a, b)
  unless (a.is_a?(Hash) && b.is_a?(Hash) && a.keys == b.keys) || (a.is_a?(Array) && b.is_a?(Array) && a.size == b.size)
    raise ArgumentError, "Arguments must be Hashes with identical keys or Arrays of the same size"
  end
  sum = 0
  a.keys.each { |k| sum += (a[k] - b[k]) ** 2 } if a.is_a?(Hash)
  a.each_with_index { |v, i| sum += (a[i] - b[i]) ** 2 } if a.is_a?(Array)
  sqrt(sum)
end

#multiple_regression(dx, dy, dz) ⇒ Object 



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# File 'lib/paleta/core_ext/math.rb', line 12

def multiple_regression(dx, dy, dz)
  regression = {}
  regression[:slope], regression[:offset] = {}, {}
  size = dx.size

  raise "arguments not same length!" unless size == dy.size && size == dz.size

  if size == 1
    regression[:slope] = { :x => dx[0], :y => dy[0], :z => dz[0] }
    regression[:offset] = { :x => 0, :y => 0, :z => 0 }
    return regression
  end

  sxx = syy = szz = sxy = szx = syz = sx = sy = sz = 0
  dx.zip(dy, dz).each do |x, y, z|
    sxx += x ** 2
    syy += y ** 2
    szz += z ** 2
    sxy += x * y
    szx += z * x
    syz += y * z
    sx  += x
    sy  += y
    sz  += z
  end

  regression[:slope][:x] = ( size * sxy - sx * sz ) / ( size * sxx - sx ** 2 ).to_f
  regression[:slope][:y] = ( size * syz - sz * sy ) / ( size * syy - sz ** 2 ).to_f
  regression[:slope][:z] = ( size * syz - sz * sy ) / ( size * szz - sy ** 2 ).to_f

  regression[:offset][:x] = (sz - regression[:slope][:x] * sx) / size
  regression[:offset][:y] = (sy - regression[:slope][:y] * sz) / size
  regression[:offset][:z] = (sx - regression[:slope][:z] * sy) / size

  regression
end