Python nn.dropout函数代码示例

 def testInvalidKeepProb(self):
     x_dim = 40
     y_dim = 30
     t = constant_op.constant(1.0, shape=[x_dim, y_dim], dtype=dtypes.float32)
     with self.assertRaises(ValueError):
         nn.dropout(t, -1.0)
     with self.assertRaises(ValueError):
         nn.dropout(t, 1.1)
     with self.assertRaises(ValueError):
         nn.dropout(t, [0.0, 1.0])
     with self.assertRaises(ValueError):
         nn.dropout(t, array_ops.placeholder(dtypes.float64))
     with self.assertRaises(ValueError):
         nn.dropout(t, array_ops.placeholder(dtypes.float32, shape=[2]))

def dropout(inputs,
            keep_prob=0.5,
            noise_shape=None,
            is_training=True,
            outputs_collections=None,
            scope=None):
  """Returns a dropout op applied to the input.
  With probability `keep_prob`, outputs the input element scaled up by
  `1 / keep_prob`, otherwise outputs `0`.  The scaling is so that the expected
  sum is unchanged.
  Args:
    inputs: the tensor to pass to the nn.dropout op.
    keep_prob: A scalar `Tensor` with the same type as x. The probability
      that each element is kept.
    noise_shape: A 1-D `Tensor` of type `int32`, representing the
      shape for randomly generated keep/drop flags.
    is_training: A bool `Tensor` indicating whether or not the model
      is in training mode. If so, dropout is applied and values scaled.
      Otherwise, inputs is returned.
    outputs_collections: collection to add the outputs.
    scope: Optional scope for op_scope.
  Returns:
    a tensor representing the output of the operation.
  """
  with ops.op_scope([inputs], scope, 'Dropout') as sc:
    is_training = ops.convert_to_tensor(is_training)
    outputs = control_flow_ops.cond(
        is_training,
        lambda: nn.dropout(inputs, keep_prob, noise_shape),
        lambda: inputs)
    return utils.collect_named_outputs(outputs_collections, sc, outputs)

 def testShapedDropout(self):
   # Runs dropout with 0-1 tensor 10 times, sum the number of ones and validate
   # that it is producing approximately the right number of ones over a large
   # number of samples, based on the keep probability. This time with shaped
   # noise.
   x_dim = 40 * 30
   y_dim = 3
   num_iter = 10
   for keep_prob in [0.1, 0.5, 0.8]:
     with self.test_session():
       t = constant_op.constant(1.0,
                                shape=[x_dim, y_dim],
                                dtype=types.float32)
       dropout = nn.dropout(t, keep_prob, noise_shape=[x_dim, 1])
       self.assertEqual([x_dim, y_dim], dropout.get_shape())
       final_count = 0
       for _ in xrange(0, num_iter):
         value = dropout.eval()
         final_count += np.count_nonzero(value)
         # Verifies that there are only two values: 0 and 1/keep_prob.
         sorted_value = np.unique(np.sort(value))
         self.assertEqual(0, sorted_value[0])
         self.assertAllClose(1 / keep_prob, sorted_value[1])
     # Check that we are in the 15% error range
     expected_count = x_dim * y_dim * keep_prob * num_iter
     rel_error = math.fabs(final_count - expected_count) / expected_count
     print rel_error
     self.assertTrue(rel_error < 0.15)

 def testShapedDropoutUnknownShape(self):
     x_dim = 40
     y_dim = 30
     keep_prob = 0.5
     x = constant_op.constant(1.0, shape=[x_dim, y_dim], dtype=dtypes.float32)
     dropout_x = nn.dropout(x, keep_prob, noise_shape=array_ops.placeholder(dtypes.int32))
     self.assertEqual(x.get_shape(), dropout_x.get_shape())

 def call(self, inputs, training=False):
     if isinstance(training, bool):
         training_bool = training
     else:
         training_bool = tensor_util.constant_value(training)
     if training_bool is False:
         return array_ops.identity(inputs)
     dropped_inputs = nn.dropout(inputs, 1 - self.rate, noise_shape=self.noise_shape, seed=self.seed)
     if training_bool is True:
         return dropped_inputs
     return control_flow_ops.cond(training, lambda: dropped_inputs, lambda: inputs)

 def testShapedDropoutCorrelation(self):
     # Runs a shaped dropout and tests that the correlations are correct.
     x_dim = 40
     y_dim = 30
     num_iter = 10
     for keep_prob in [0.1, 0.5, 0.8]:
         with self.test_session():
             t = constant_op.constant(1.0, shape=[x_dim, y_dim], dtype=dtypes.float32)
             dropout = nn.dropout(t, keep_prob, noise_shape=[x_dim, 1])
             self.assertEqual([x_dim, y_dim], dropout.get_shape())
             for _ in xrange(0, num_iter):
                 value = dropout.eval()
                 # Verifies that each y column as only one type of activation.
                 for i in xrange(x_dim):
                     sorted_value = np.unique(np.sort(value[i, :]))
                     self.assertEqual(sorted_value.size, 1)

 def testShapedDropoutShapeError(self):
     # Runs shaped dropout and verifies an error is thrown on misshapen noise.
     x_dim = 40
     y_dim = 30
     keep_prob = 0.5
     t = constant_op.constant(1.0, shape=[x_dim, y_dim], dtype=dtypes.float32)
     with self.assertRaises(ValueError):
         _ = nn.dropout(t, keep_prob, noise_shape=[x_dim, y_dim + 10])
     with self.assertRaises(ValueError):
         _ = nn.dropout(t, keep_prob, noise_shape=[x_dim, y_dim, 5])
     with self.assertRaises(ValueError):
         _ = nn.dropout(t, keep_prob, noise_shape=[x_dim + 3])
     with self.assertRaises(ValueError):
         _ = nn.dropout(t, keep_prob, noise_shape=[x_dim])
     # test that broadcasting proceeds
     _ = nn.dropout(t, keep_prob, noise_shape=[y_dim])
     _ = nn.dropout(t, keep_prob, noise_shape=[1, y_dim])
     _ = nn.dropout(t, keep_prob, noise_shape=[x_dim, 1])
     _ = nn.dropout(t, keep_prob, noise_shape=[1, 1])

def dropout(tensor_in, prob, name=None):
    """Adds dropout node and stores probability tensor into graph collection.

    Args:
        tensor_in: Input tensor.
        prob: Float or Tensor.

    Returns:
        Tensor of the same shape of `tensor_in`.

    Raises:
        ValueError: If `keep_prob` is not in `(0, 1]`.
    """
    with ops.op_scope([tensor_in], name, "dropout") as name:
        if isinstance(prob, float):
            prob = vs.get_variable("prob", [],
                                   initializer=init_ops.constant_initializer(prob),
                                   trainable=False)
        ops.add_to_collection(DROPOUTS, prob)
        return nn.dropout(tensor_in, prob)

  def test_conv_bn_dropout(self):
    """Test dropout precision of convolution batch norm graph."""
    if test.is_gpu_available(cuda_only=True):
      random_seed.set_random_seed(0)
      x = _input([2, 8, 8, 1])
      y = _conv_bn(x)
      y = nn.dropout(y, rate=0.5)
      y = _conv_bn(y)
      y = array_ops.identity(y)
      optimizer = gradient_descent.GradientDescentOptimizer(learning_rate=0.01)
      g = optimizer.compute_gradients(y, [x])
      output = (y, g)

      output_val_ref, output_val, cost_graph = self._run(output)
      node_map = _build_node_map(cost_graph.node)
      self._assert_output_fp16(node_map, 'Conv2D')
      self._assert_output_fp16(node_map, 'FusedBatchNorm')
      self._assert_output_fp16(node_map, 'dropout/mul')
      self._assert_output_fp16(node_map, 'Conv2D_1')

      output_val_ref, output_val, cost_graph = self._run(output)
      self.assertAllClose(output_val_ref, output_val, atol=1e-3, rtol=1e-3)

 def dropped_inputs():
   return nn.dropout(inputs, 1  - self.rate,
                     noise_shape=self._get_noise_shape(inputs),
                     seed=self.seed)

 def _dropout():
   return nn.dropout(inputs, keep_prob, noise_shape)