Class: Array

Inherits:
Object show all
Includes:
Statsample::VectorShorthands
Defined in:
lib/statsample.rb,
lib/statsample/vector.rb,
lib/statsample/dataset.rb

Instance Method Summary collapse

Methods included from Statsample::VectorShorthands

#to_numeric, #to_scale, #to_vector

Instance Method Details

#mean ⇒ Object 



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# File 'lib/statsample.rb', line 61

def mean
  self.sum / size
end

#prefix(s) ⇒ Object

:nodoc:



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# File 'lib/statsample/dataset.rb', line 13

def prefix(s) # :nodoc:
  self.collect{|c| s+c.to_s }
end

#sd ⇒ Object

Calculate sample standard deviation



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# File 'lib/statsample.rb', line 78

def sd
  m ||= mean
  Math::sqrt(variance_sample(m))
end

#suffix(s) ⇒ Object

:nodoc:



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# File 'lib/statsample/dataset.rb', line 16

def suffix(s) # :nodoc:
  self.collect{|c| c.to_s+s }
end

#sum ⇒ Object 



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

def sum
  inject(:+)
end

#sum_of_squares(m = nil) ⇒ Object

Calcualte sum of squares



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# File 'lib/statsample.rb', line 66

def sum_of_squares(m=nil)
  m ||= mean
  self.inject(0) {|a,x| a + (x-m).square }
end

#variance_sample(m = nil) ⇒ Object

Calculate sample variance



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# File 'lib/statsample.rb', line 72

def variance_sample(m=nil)
  m ||= mean
  sum_of_squares(m).quo(size - 1)
end