Class: Array

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

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.average(vectors) ⇒ Object 



5
6
7
8
9
10
11
12
13
 
# File 'lib/best_thumbnail.rb', line 5

def self.average(vectors)
  result = Array.new(vectors.first.size, 0)
  vectors.each do |vector|
    vector.each_with_index do |value,index|  
      result[index] += value
    end
  end
  result.map!{|value| value.to_f / vectors.size}
end

Instance Method Details

#variance(average) ⇒ Object 



15
16
17
18
19
20
21
 
# File 'lib/best_thumbnail.rb', line 15

def variance(average)
  result = 0
  self.each_with_index do |value,index|
    result += (value - average[index])**2
  end
  Math.sqrt(result.to_f / average.size)
end