Class: SVMKit::PolynomialModel::FactorizationMachineClassifier

Inherits:
Object
  • Object
show all
Includes:
Base::BaseEstimator, Base::Classifier
Defined in:
lib/svmkit/polynomial_model/factorization_machine_classifier.rb

Overview

FactorizationMachineClassifier is a class that implements Factorization Machine with stochastic gradient descent (SGD) optimization. For multiclass classification problem, it uses one-vs-the-rest strategy.

Reference

    1. Rendle, “Factorization Machines with libFM,” ACM Transactions on Intelligent Systems and Technology, vol. 3 (3), pp. 57:1–57:22, 2012.

    1. Rendle, “Factorization Machines,” Proceedings of the 10th IEEE International Conference on Data Mining (ICDM’10), pp. 995–1000, 2010.

Examples:

estimator =
  SVMKit::PolynomialModel::FactorizationMachineClassifier.new(
   n_factors: 10, loss: 'hinge', reg_param_bias: 0.001, reg_param_weight: 0.001, reg_param_factor: 0.001,
   max_iter: 5000, batch_size: 50, random_seed: 1)
estimator.fit(training_samples, traininig_labels)
results = estimator.predict(testing_samples)

Instance Attribute Summary collapse

Attributes included from Base::BaseEstimator

#params

Instance Method Summary collapse

Methods included from Base::Classifier

#score

Constructor Details

#initialize(n_factors: 2, loss: 'hinge', reg_param_bias: 1.0, reg_param_weight: 1.0, reg_param_factor: 1.0, init_std: 0.1, max_iter: 1000, batch_size: 10, random_seed: nil) ⇒ FactorizationMachineClassifier

Create a new classifier with Factorization Machine.

Parameters:

  • n_factors (Integer) (defaults to: 2) —

    The maximum number of iterations.

  • loss (String) (defaults to: 'hinge') —

    The loss function (‘hinge’ or ‘logistic’).

  • reg_param_bias (Float) (defaults to: 1.0) —

    The regularization parameter for bias term.

  • reg_param_weight (Float) (defaults to: 1.0) —

    The regularization parameter for weight vector.

  • reg_param_factor (Float) (defaults to: 1.0) —

    The regularization parameter for factor matrix.

  • init_std (Float) (defaults to: 0.1) —

    The standard deviation of normal random number for initialization of factor matrix.

  • max_iter (Integer) (defaults to: 1000) —

    The maximum number of iterations.

  • batch_size (Integer) (defaults to: 10) —

    The size of the mini batches.

  • random_seed (Integer) (defaults to: nil) —

    The seed value using to initialize the random generator.



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 59

def initialize(n_factors: 2, loss: 'hinge', reg_param_bias: 1.0, reg_param_weight: 1.0, reg_param_factor: 1.0,
               init_std: 0.1, max_iter: 1000, batch_size: 10, random_seed: nil)
  @params = {}
  @params[:n_factors] = n_factors
  @params[:loss] = loss
  @params[:reg_param_bias] = reg_param_bias
  @params[:reg_param_weight] = reg_param_weight
  @params[:reg_param_factor] = reg_param_factor
  @params[:init_std] = init_std
  @params[:max_iter] = max_iter
  @params[:batch_size] = batch_size
  @params[:random_seed] = random_seed
  @params[:random_seed] ||= srand
  @factor_mat = nil
  @weight_vec = nil
  @bias_term = nil
  @classes = nil
  @rng = Random.new(@params[:random_seed])
end

Instance Attribute Details

#bias_term ⇒ Numo::DFloat (readonly)

Return the bias term for Factoriazation Machine.

Returns:

  • (Numo::DFloat) —

    (shape: [n_classes])



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 38

def bias_term
  @bias_term
end

#classes ⇒ Numo::Int32 (readonly)

Return the class labels.

Returns:

  • (Numo::Int32) —

    (shape: [n_classes])



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 42

def classes
  @classes
end

#factor_mat ⇒ Numo::DFloat (readonly)

Return the factor matrix for Factorization Machine.

Returns:

  • (Numo::DFloat) —

    (shape: [n_classes, n_factors, n_features])



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 30

def factor_mat
  @factor_mat
end

#rng ⇒ Random (readonly)

Return the random generator for random sampling.

Returns:

  • (Random) 


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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 46

def rng
  @rng
end

#weight_vec ⇒ Numo::DFloat (readonly)

Return the weight vector for Factorization Machine.

Returns:

  • (Numo::DFloat) —

    (shape: [n_classes, n_features])



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 34

def weight_vec
  @weight_vec
end

Instance Method Details

#decision_function(x) ⇒ Numo::DFloat

Calculate confidence scores for samples.

Parameters:

  • x (Numo::DFloat) —

    (shape: [n_samples, n_features]) The samples to compute the scores.

Returns:

  • (Numo::DFloat) —

    (shape: [n_samples]) Confidence score per sample.



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 113

def decision_function(x)
  linear_term = @bias_term + x.dot(@weight_vec.transpose)
  factor_term = if @classes.size <= 2
                  0.5 * (@factor_mat.dot(x.transpose)**2 - (@factor_mat**2).dot(x.transpose**2)).sum
                else
                  0.5 * (@factor_mat.dot(x.transpose)**2 - (@factor_mat**2).dot(x.transpose**2)).sum(1).transpose
                end
  linear_term + factor_term
end

#fit(x, y) ⇒ FactorizationMachineClassifier

Fit the model with given training data.

Parameters:

  • x (Numo::DFloat) —

    (shape: [n_samples, n_features]) The training data to be used for fitting the model.

  • y (Numo::Int32) —

    (shape: [n_samples]) The labels to be used for fitting the model.

Returns:



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 84

def fit(x, y)
  @classes = Numo::Int32[*y.to_a.uniq.sort]
  n_classes = @classes.size
  _n_samples, n_features = x.shape

  if n_classes > 2
    @factor_mat = Numo::DFloat.zeros(n_classes, @params[:n_factors], n_features)
    @weight_vec = Numo::DFloat.zeros(n_classes, n_features)
    @bias_term = Numo::DFloat.zeros(n_classes)
    n_classes.times do |n|
      bin_y = Numo::Int32.cast(y.eq(@classes[n])) * 2 - 1
      factor, weight, bias = binary_fit(x, bin_y)
      @factor_mat[n, true, true] = factor
      @weight_vec[n, true] = weight
      @bias_term[n] = bias
    end
  else
    negative_label = y.to_a.uniq.sort.first
    bin_y = Numo::Int32.cast(y.ne(negative_label)) * 2 - 1
    @factor_mat, @weight_vec, @bias_term = binary_fit(x, bin_y)
  end

  self
end

#marshal_dump ⇒ Hash

Dump marshal data.

Returns:

  • (Hash) —

    The marshal data about FactorizationMachineClassifier



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 152

def marshal_dump
  { params: @params,
    factor_mat: @factor_mat,
    weight_vec: @weight_vec,
    bias_term: @bias_term,
    classes: @classes,
    rng: @rng }
end

#marshal_load(obj) ⇒ nil

Load marshal data.

Returns:

  • (nil) 


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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 163

def marshal_load(obj)
  @params = obj[:params]
  @factor_mat = obj[:factor_mat]
  @weight_vec = obj[:weight_vec]
  @bias_term = obj[:bias_term]
  @classes = obj[:classes]
  @rng = obj[:rng]
  nil
end

#predict(x) ⇒ Numo::Int32

Predict class labels for samples.

Parameters:

  • x (Numo::DFloat) —

    (shape: [n_samples, n_features]) The samples to predict the labels.

Returns:

  • (Numo::Int32) —

    (shape: [n_samples]) Predicted class label per sample.



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 127

def predict(x)
  return Numo::Int32.cast(decision_function(x).ge(0.0)) * 2 - 1 if @classes.size <= 2

  n_samples, = x.shape
  decision_values = decision_function(x)
  Numo::Int32.asarray(Array.new(n_samples) { |n| @classes[decision_values[n, true].max_index] })
end

#predict_proba(x) ⇒ Numo::DFloat

Predict probability for samples.

Parameters:

  • x (Numo::DFloat) —

    (shape: [n_samples, n_features]) The samples to predict the probailities.

Returns:

  • (Numo::DFloat) —

    (shape: [n_samples, n_classes]) Predicted probability of each class per sample.



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# File 'lib/svmkit/polynomial_model/factorization_machine_classifier.rb', line 139

def predict_proba(x)
  proba = 1.0 / (Numo::NMath.exp(-decision_function(x)) + 1.0)
  return (proba.transpose / proba.sum(axis: 1)).transpose if @classes.size > 2

  n_samples, = x.shape
  probs = Numo::DFloat.zeros(n_samples, 2)
  probs[true, 1] = proba
  probs[true, 0] = 1.0 - proba
  probs
end