Class: Array

Inherits:
Object
  • Object
show all
Defined in:
lib/mork/extensions.rb

Instance Method Summary collapse

Instance Method Details

#mean ⇒ Object 



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# File 'lib/mork/extensions.rb', line 2

def mean
  @the_sample_mean ||= inject(:+)/length.to_f
end

#sample_variance ⇒ Object 



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# File 'lib/mork/extensions.rb', line 6

def sample_variance
  sum = inject(0){|accum, i| accum + (i-mean)**2 }
  sum/(length - 1).to_f
end

#stdev ⇒ Object 



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# File 'lib/mork/extensions.rb', line 11

def stdev
  Math.sqrt sample_variance
end