Module: MassIndex

Included in:
Array
Defined in:
lib/ruby-technical-analysis/indicators/mass_index.rb

Overview

Mass Index indicator Returns a singular current value

Instance Method Summary collapse

Instance Method Details

#mass_index(period) ⇒ Object 



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# File 'lib/ruby-technical-analysis/indicators/mass_index.rb', line 8

def mass_index(period)
  highs = []
  lows = []

  each do |i|
    highs << i[0]
    lows << i[1]
  end

  if highs.size < period
    raise ArgumentError,
          "High array passed to Mass Index cannot be less than (2 * period + 1)."
  end

  if lows.size < period
    raise ArgumentError,
          "Low array passed to Mass Index cannot be less than (2 * period + 1)."
  end

  full_period = (2 * period + 1)
  highs = highs.last(full_period)
  lows = lows.last(full_period)

  hml_arr = []
  hml_ema_arr = []
  hml_ema_ema_arr = []

  (0..(highs.size - 1)).each do |i|
    hml_arr << highs[i] - lows[i]
  end

  low_multiple = (2.0 / (period + 1)).truncate(4)
  high_multiple = 1 - low_multiple

  (0..hml_arr.length - 1).each do |i|
    hml_ema_arr << if i.zero?
                     hml_arr[0].truncate(4)
                   else
                     ((hml_arr[i] * low_multiple) + (hml_ema_arr[i - 1] * high_multiple)).truncate(4)
                   end
  end

  (0..period + 1).each do |i|
    hml_ema_ema_arr << if i.zero?
                         hml_ema_arr[period - i - 1]
                       else
                         ((hml_ema_arr[period + i - 1] * 0.2) + (hml_ema_ema_arr[-1] * 0.8)).round(4)
                       end
  end

  ema_period_two_div_ema_period = []

  mi = 0.0
  (0..2).each do |i|
    ema_period_two_div_ema_period <<
      ((hml_ema_arr[(period * 2) + i - 2]) / (hml_ema_ema_arr[period + i - 1])).round(4)
    mi += ((hml_ema_arr[(period * 2) + i - 2]) / (hml_ema_ema_arr[period + i - 1])).round(4)
  end

  mi.round(4)
end