Module: NumericArray::InstanceMethods

Defined in:
lib/numeric_array.rb

Constant Summary collapse

NUMERIC_REGEX = 
/^-?\d+.?\d*e?-?\d*$/

Instance Method Summary collapse

Instance Method Details

#average ⇒ Object Also known as: avg, mean

average of an array of numbers



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# File 'lib/numeric_array.rb', line 13

def average
  check_numeric_array!
  a = numerify
  a.sum / length.to_f
end

#check_numeric_array! ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/numeric_array.rb', line 44

def check_numeric_array!
  raise ArgumentError, "Array cannot have the following non-numeric elements: #{non_numeric_elements.collect(&:inspect).join(", ")}" unless numeric_array?
end

#non_numeric_elements ⇒ Object 



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# File 'lib/numeric_array.rb', line 53

def non_numeric_elements
  self.select{|obj| !(obj.kind_of?(Numeric) or obj.to_s =~ NUMERIC_REGEX)}
end

#numeric_array? ⇒ Boolean Also known as: numeric?

Returns:

  • (Boolean) 


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# File 'lib/numeric_array.rb', line 48

def numeric_array?
  !self.detect{|obj| !(obj.kind_of?(Numeric) or obj.to_s =~ NUMERIC_REGEX) }
end

#numerify ⇒ Object 



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# File 'lib/numeric_array.rb', line 57

def numerify
  self.collect do |obj|
    if obj.kind_of? Numeric
      obj
    elsif obj.to_s =~ NUMERIC_REGEX
      obj.to_f
    else
      raise ArgumentError, "Array element #{obj.inspect} cannot be converted into a numeric value"
    end
  end
end

#numerify! ⇒ Object 



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# File 'lib/numeric_array.rb', line 69

def numerify!
  self.replace(numerify)
end

#sample_standard_deviation ⇒ Object Also known as: sample_std_dev 



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# File 'lib/numeric_array.rb', line 39

def sample_standard_deviation
  standard_deviation(true)
end

#sample_variance ⇒ Object 



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# File 'lib/numeric_array.rb', line 29

def sample_variance
  variance(true)
end

#standard_deviation(sample = false) ⇒ Object Also known as: std_dev

standard deviation of an array of numbers



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# File 'lib/numeric_array.rb', line 34

def standard_deviation(sample = false)
  Math.sqrt(self.variance(sample))
end

#sum ⇒ Object 



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# File 'lib/numeric_array.rb', line 6

def sum
  check_numeric_array!
  a = numerify
  a.inject(0) {|sum, value| sum + value}
end

#variance(sample = false) ⇒ Object

variance of an array of numbers



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# File 'lib/numeric_array.rb', line 22

def variance(sample = false)
  a = numerify
  avg = a.average
  sum = a.inject(0) { |sum, value| sum + (value - avg) ** 2}
  (1 / (a.length.to_f - (sample ? 1 : 0)) * sum)
end