Class: Chainer::Functions::Evaluation::Accuracy

Inherits:
Chainer::Function show all
Defined in:
lib/chainer/functions/evaluation/accuracy.rb

Instance Attribute Summary

Attributes inherited from Chainer::Function

#inputs, #output_data, #outputs, #owned_node, #rank, #retain_after_backward

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Chainer::Function

#backward, #backward_cpu, #backward_gpu, #call, #forward_cpu, #forward_gpu, #label, #node, #retain_inputs, #retain_outputs

Constructor Details

#initialize(ignore_label: nil) ⇒ Accuracy

Returns a new instance of Accuracy.


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# File 'lib/chainer/functions/evaluation/accuracy.rb', line 9

def initialize(ignore_label: nil)
  @ignore_label = ignore_label
end

Class Method Details

.accuracy(y, t, ignore_label: nil) ⇒ Object 


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# File 'lib/chainer/functions/evaluation/accuracy.rb', line 5

def self.accuracy(y, t, ignore_label: nil)
  self.new(ignore_label: ignore_label).(y, t)
end

Instance Method Details

#forward(inputs) ⇒ Object 


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# File 'lib/chainer/functions/evaluation/accuracy.rb', line 13

def forward(inputs)
  y, t = inputs
  xm = Chainer.get_array_module(*inputs)
  if @ignore_label
    mask = t.eq(@ignore_label)
    ignore_cnt = mask.count

    pred = y.max_index(axis: 1) - xm::Int32.new(y.shape[0]).seq(0, y.shape[1])
    pred = pred.reshape(*t.shape)
    pred[mask] = @ignore_label
    count = pred.eq(t).count - ignore_cnt

    total = t.size - ignore_cnt

    if total == 0
      [y.class.cast(0.0)]
    else
      [y.class.cast(count.to_f / total)]
    end
  else
    pred = y.max_index(axis: 1) - xm::Int32.new(y.shape[0]).seq(0, y.shape[1])
    pred = pred.reshape(*t.shape)

    [y.class.cast(y.class[pred.eq(t)].mean)]
  end
end