Integration of backward pass for dropout

Author: milancurcic

src/nf/nf_layer_submodule.f90

@@ -25,12 +25,14 @@ pure module subroutine backward_1d(self, previous, gradient)
 
       type is(dense_layer)
 
-        ! Upstream layers permitted: input1d, dense, flatten
+        ! Upstream layers permitted: input1d, dense, dropout, flatten
         select type(prev_layer => previous % p)
           type is(input1d_layer)
             call this_layer % backward(prev_layer % output, gradient)
           type is(dense_layer)
             call this_layer % backward(prev_layer % output, gradient)
+          type is(dropout_layer)
+            call this_layer % backward(prev_layer % output, gradient)
           type is(flatten_layer)
             call this_layer % backward(prev_layer % output, gradient)
         end select
@@ -116,12 +118,14 @@ module subroutine forward(self, input)
 
       type is(dense_layer)
 
-        ! Upstream layers permitted: input1d, dense, flatten
+        ! Upstream layers permitted: input1d, dense, dropout, flatten
         select type(prev_layer => input % p)
           type is(input1d_layer)
             call this_layer % forward(prev_layer % output)
           type is(dense_layer)
             call this_layer % forward(prev_layer % output)
+          type is(dropout_layer)
+            call this_layer % forward(prev_layer % output)
           type is(flatten_layer)
             call this_layer % forward(prev_layer % output)
         end select
@@ -299,6 +303,8 @@ elemental module function get_num_params(self) result(num_params)
         num_params = 0
       type is (dense_layer)
         num_params = this_layer % get_num_params()
+      type is (dropout_layer)
+        num_params = size(this_layer % mask)
       type is (conv2d_layer)
         num_params = this_layer % get_num_params()
       type is (maxpool2d_layer)
@@ -324,6 +330,8 @@ module function get_params(self) result(params)
          ! No parameters to get.
       type is (dense_layer)
         params = this_layer % get_params()
+      type is (dropout_layer)
+        ! No parameters to get.
       type is (conv2d_layer)
         params = this_layer % get_params()
       type is (maxpool2d_layer)
@@ -349,6 +357,8 @@ module function get_gradients(self) result(gradients)
         ! No gradients to get.
       type is (dense_layer)
         gradients = this_layer % get_gradients()
+      type is (dropout_layer)
+        ! No gradients to get.
       type is (conv2d_layer)
         gradients = this_layer % get_gradients()
       type is (maxpool2d_layer)
@@ -396,6 +406,11 @@ module subroutine set_params(self, params)
       type is (dense_layer)
         call this_layer % set_params(params)
 
+      type is (dropout_layer)
+        ! No parameters to set.
+        write(stderr, '(a)') 'Warning: calling set_params() ' &
+          // 'on a zero-parameter layer; nothing to do.'
+
       type is (conv2d_layer)
         call this_layer % set_params(params)
 

src/nf/nf_network_submodule.f90

@@ -135,6 +135,8 @@ module subroutine backward(self, output, loss)
         select type(next_layer => self % layers(n + 1) % p)
           type is(dense_layer)
             call self % layers(n) % backward(self % layers(n - 1), next_layer % gradient)
+          type is(dropout_layer)
+            call self % layers(n) % backward(self % layers(n - 1), next_layer % gradient)
           type is(conv2d_layer)
             call self % layers(n) % backward(self % layers(n - 1), next_layer % gradient)
           type is(flatten_layer)