Class: Newral::Training::HillClimbing

Inherits:
Object
  • Object
show all
Defined in:
lib/newral/training/hill_climbing.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(input: [], output: [], iterations: 10**5, klass: Newral::Functions::Polynomial, klass_args: {}, start_function: nil) ⇒ HillClimbing

Returns a new instance of HillClimbing.



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

def initialize( input: [], output: [], iterations:10**5, klass: Newral::Functions::Polynomial, klass_args: {}, start_function: nil  )
  @input = input
  @output = output
  @iterations = iterations
  @klass = klass
  @klass_args = klass_args
  @best_function = start_function
  @needed_iterations = 0
end

Instance Attribute Details

#best_error ⇒ Object (readonly)

Returns the value of attribute best_error.



4
5
6
 
# File 'lib/newral/training/hill_climbing.rb', line 4

def best_error
  @best_error
end

#best_function ⇒ Object (readonly)

Returns the value of attribute best_function.



4
5
6
 
# File 'lib/newral/training/hill_climbing.rb', line 4

def best_function
  @best_function
end

#input ⇒ Object (readonly)

Returns the value of attribute input.



4
5
6
 
# File 'lib/newral/training/hill_climbing.rb', line 4

def input
  @input
end

#needed_iterations ⇒ Object (readonly)

Returns the value of attribute needed_iterations.



4
5
6
 
# File 'lib/newral/training/hill_climbing.rb', line 4

def needed_iterations
  @needed_iterations
end

Instance Method Details

#process(start_fresh: false, max_error: 0.01) ⇒ Object 



16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
 
# File 'lib/newral/training/hill_climbing.rb', line 16

def process( start_fresh: false, max_error:0.01 )
  @best_function = case 
    when start_fresh then @klass.create_random( @klass_args ) 
    when  @best_function then @best_function
  else 
     @klass.create_random( @klass_args )
  end
  
  function = @best_function.dup.move_random( @klass_args )
  @best_error = @best_function.calculate_error( input: @input, output: @output )
  number_of_directions = @best_function.number_of_directions
  step_sizes = [1]*number_of_directions
  acceleration = 1.2
  candidates = [
    -acceleration,
    -1/acceleration,
    0,
    1/acceleration,
    acceleration
  ]
  i=0 
  best_local_function = @best_function.dup
  before_error = 99999
  after_error = 1
  moved = true
  while i<@iterations  && @best_error > max_error 
    moved = false
    before_error = function.calculate_error( input: @input, output: @output )
    number_of_directions.times do |direction|
      best_candidate = -1
      best_candidate_error = 9999999
      candidates.each do |candidate| 
        temp_function = function.dup.move( direction: direction, step: step_sizes[ direction ]*candidate)
        error = temp_function.calculate_error( input: @input, output: @output )
        if error < best_candidate_error
          best_candidate = candidate
          best_candidate_error = error
          if error < @best_error
            @best_error = best_candidate_error
            @best_function = temp_function.dup
          end
        end 
      end
      if best_candidate == 0
        step_sizes[direction] = step_sizes[direction] / acceleration # take it slower
      else
        moved = true
        function.move( direction: direction, step: step_sizes[ direction ]*best_candidate )
        # puts "moving #{direction} by #{(step_sizes[ direction ]*candidates[best_candidate]).to_s}"
        step_sizes[direction] = step_sizes[ direction ] * best_candidate # accelerate
      end
    end
    after_error = function.calculate_error( input: @input, output: @output )
    i=i+1
  end
  @needed_iterations = i 
  @best_function
end