Class: Svm::Scaler

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data) ⇒ Scaler

Returns a new instance of Scaler.



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# File 'lib/svm/scaler.rb', line 16

def initialize(data)
  @data = data

  @num_samples = data.size
  @num_features = data.first.size - 1
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/svm/scaler.rb', line 5

def data
  @data
end

#num_features ⇒ Object (readonly)

Returns the value of attribute num_features.



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# File 'lib/svm/scaler.rb', line 7

def num_features
  @num_features
end

#num_samples ⇒ Object (readonly)

Returns the value of attribute num_samples.



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# File 'lib/svm/scaler.rb', line 6

def num_samples
  @num_samples
end

Class Method Details

.load(path) ⇒ Object 



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# File 'lib/svm/scaler.rb', line 78

def self.load(path)
  YAML.load(File.read(path))
end

.scale(data) ⇒ Object 



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# File 'lib/svm/scaler.rb', line 9

def self.scale(data)
  instance = self.new(data)
  instance.scale!

  instance
end

Instance Method Details

#labels ⇒ Object 



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# File 'lib/svm/scaler.rb', line 55

def labels
  values_for_feature 0
end

#release_data! ⇒ Object

Release references to data so it can be garbage collected



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# File 'lib/svm/scaler.rb', line 68

def release_data!
  @data = nil
end

#save(path) ⇒ Object 



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# File 'lib/svm/scaler.rb', line 72

def save(path)
  File.open(path, 'w+') do |f|
    f.write(YAML.dump(self))
  end
end

#scale(sample, with_labels = false) ⇒ Object 



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# File 'lib/svm/scaler.rb', line 37

def scale(sample, with_labels = false)
  # If the sample does't have label it should be accessed
  # one more position to the left
  offset = with_labels ? 0 : -1

  (1..num_features).each do |i|
    new_value = sample[i+offset].to_f - zero[i]
    new_value = new_value / unit[i] unless unit[i] == 0
    sample[i+offset] = new_value
  end

  sample
end

#scale! ⇒ Object 



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# File 'lib/svm/scaler.rb', line 23

def scale!
  (1..num_features).each do |i|
    max = values_for_feature(i).compact.max
    min = values_for_feature(i).compact.min

    diff = (max - min).to_f

    unit[i] = diff/2.0
    zero[i] = min + unit[i]
  end

  data.collect { |sample| scale(sample, true) }
end

#unit ⇒ Object 



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# File 'lib/svm/scaler.rb', line 59

def unit
  @unit ||= []
end

#values_for_feature(i) ⇒ Object 



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# File 'lib/svm/scaler.rb', line 51

def values_for_feature(i)
  @data.collect { |sample| sample[i] }
end

#zero ⇒ Object 



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# File 'lib/svm/scaler.rb', line 63

def zero
  @zero ||= []
end