Class: TechnicalAnalysis::Mi

Inherits:
Indicator show all
Defined in:
lib/technical_analysis/indicators/mi.rb

Overview

Mass Index

Class Method Summary collapse

Methods inherited from Indicator

find, roster

Class Method Details

.calculate(data, ema_period: 9, sum_period: 25) ⇒ Array<MiValue>

Calculates the mass index (MI) for the data over the given period en.wikipedia.org/wiki/Mass_index

Parameters:

  • data (Array) —

    Array of hashes with keys (:date_time, :high, :low)

  • ema_period (Integer) (defaults to: 9) —

    The given period to calculate the EMA and EMA of EMA

  • sum_period (Integer) (defaults to: 25) —

    The given period to calculate the sum of EMA ratios

Returns:

  • (Array<MiValue>) —

    An array of MiValue instances



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# File 'lib/technical_analysis/indicators/mi.rb', line 53

def self.calculate(data, ema_period: 9, sum_period: 25)
  ema_period = ema_period.to_i
  sum_period = sum_period.to_i
  Validation.validate_numeric_data(data, :high, :low)
  Validation.validate_length(data, min_data_size(ema_period: ema_period, sum_period: sum_period))
  Validation.validate_date_time_key(data)

  data = data.sort_by { |row| row[:date_time] }

  double_emas = []
  high_low_diffs = []
  output = []
  ratio_of_emas = []
  single_emas = []

  data.each do |v|
    high_low_diff = v[:high] - v[:low]
    high_low_diffs << high_low_diff

    if high_low_diffs.size == ema_period
      single_ema = StockCalculation.ema(high_low_diff, high_low_diffs, ema_period, single_emas.last)
      single_emas << single_ema

      if single_emas.size == ema_period
        double_ema = StockCalculation.ema(single_emas.last, single_emas, ema_period, double_emas.last)
        double_emas << double_ema

        ratio_of_emas << (single_ema / double_ema)

        if ratio_of_emas.size == sum_period
          output << MiValue.new(date_time: v[:date_time], mi: ArrayHelper.sum(ratio_of_emas))

          double_emas.shift
          ratio_of_emas.shift
        end

        single_emas.shift
      end

      high_low_diffs.shift
    end
  end

  output.sort_by(&:date_time).reverse
end

.indicator_name ⇒ String

Returns the name of the technical indicator

Returns:

  • (String) —

    A string of the name of the technical indicator



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# File 'lib/technical_analysis/indicators/mi.rb', line 15

def self.indicator_name
  "Mass Index"
end

.indicator_symbol ⇒ String

Returns the symbol of the technical indicator

Returns:

  • (String) —

    A string of the symbol of the technical indicator



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# File 'lib/technical_analysis/indicators/mi.rb', line 8

def self.indicator_symbol
  "mi"
end

.min_data_size(ema_period: 9, sum_period: 25) ⇒ Integer

Calculates the minimum number of observations needed to calculate the technical indicator

Parameters:

  • options (Hash) —

    The options for the technical indicator

Returns:

  • (Integer) —

    Returns the minimum number of observations needed to calculate the technical indicator based on the options provided



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# File 'lib/technical_analysis/indicators/mi.rb', line 41

def self.min_data_size(ema_period: 9, sum_period: 25)
  (ema_period.to_i * 2) + sum_period.to_i - 2
end

.valid_options ⇒ Array

Returns an array of valid keys for options for this technical indicator

Returns:

  • (Array) —

    An array of keys as symbols for valid options for this technical indicator



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# File 'lib/technical_analysis/indicators/mi.rb', line 22

def self.valid_options
  i(ema_period sum_period)
end

.validate_options(options) ⇒ Boolean

Validates the provided options for this technical indicator

Parameters:

  • options (Hash) —

    The options for the technical indicator to be validated

Returns:

  • (Boolean) —

    Returns true if options are valid or raises a ValidationError if they’re not



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# File 'lib/technical_analysis/indicators/mi.rb', line 31

def self.validate_options(options)
  Validation.validate_options(options, valid_options)
end