Class: Rumale::PolynomialModel::FactorizationMachineClassifier

Inherits:
BaseFactorizationMachine show all
Includes:
Base::Classifier
Defined in:
lib/rumale/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 TIST, vol. 3 (3), pp. 57:1–57:22, 2012.

    1. Rendle, “Factorization Machines,” Proc. ICDM’10, pp. 995–1000, 2010.

Examples:

estimator =
  Rumale::PolynomialModel::FactorizationMachineClassifier.new(
   n_factors: 10, loss: 'hinge', reg_param_linear: 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_linear: 1.0, reg_param_factor: 1.0, max_iter: 1000, batch_size: 10, optimizer: nil, random_seed: nil) ⇒ FactorizationMachineClassifier

Create a new classifier with Factorization Machine.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 58

def initialize(n_factors: 2, loss: 'hinge', reg_param_linear: 1.0, reg_param_factor: 1.0,
               max_iter: 1000, batch_size: 10, optimizer: nil, random_seed: nil)
  check_params_float(reg_param_linear: reg_param_linear, reg_param_factor: reg_param_factor)
  check_params_integer(n_factors: n_factors, max_iter: max_iter, batch_size: batch_size)
  check_params_string(loss: loss)
  check_params_type_or_nil(Integer, random_seed: random_seed)
  check_params_positive(n_factors: n_factors,
                        reg_param_linear: reg_param_linear, reg_param_factor: reg_param_factor,
                        max_iter: max_iter, batch_size: batch_size)
  super
  @classes = nil
end

Instance Attribute Details

#bias_term ⇒ Numo::DFloat (readonly)

Return the bias term for Factoriazation Machine.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 37

def bias_term
  @bias_term
end

#classes ⇒ Numo::Int32 (readonly)

Return the class labels.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 41

def classes
  @classes
end

#factor_mat ⇒ Numo::DFloat (readonly)

Return the factor matrix for Factorization Machine.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 29

def factor_mat
  @factor_mat
end

#rng ⇒ Random (readonly)

Return the random generator for random sampling.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 45

def rng
  @rng
end

#weight_vec ⇒ Numo::DFloat (readonly)

Return the weight vector for Factorization Machine.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 33

def weight_vec
  @weight_vec
end

Instance Method Details

#decision_function(x) ⇒ Numo::DFloat

Calculate confidence scores for samples.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 106

def decision_function(x)
  check_sample_array(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(0)
                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.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 76

def fit(x, y)
  check_sample_array(x)
  check_label_array(y)
  check_sample_label_size(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_mat[n, true, true], @weight_vec[n, true], @bias_term[n] = partial_fit(x, bin_y)
    end
  else
    negative_label = y.to_a.uniq.min
    bin_y = Numo::Int32.cast(y.ne(negative_label)) * 2 - 1
    @factor_mat, @weight_vec, @bias_term = partial_fit(x, bin_y)
  end

  self
end

#marshal_dump ⇒ Hash

Dump marshal data.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 148

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.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 159

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.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 121

def predict(x)
  check_sample_array(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.



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# File 'lib/rumale/polynomial_model/factorization_machine_classifier.rb', line 134

def predict_proba(x)
  check_sample_array(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