Add example program on how to access internal layer parameters (#140)

Author: milancurcic

example/CMakeLists.txt

@@ -4,6 +4,7 @@ foreach(execid
  dense_mnist
  dense_from_keras
  get_set_network_params
+ network_parameters
  simple
  sine
  quadratic

example/network_parameters.f90

@@ -0,0 +1,33 @@
+program network_parameters
+ ! This program demonstrates how to access network parameters (weights and
+ ! biases) from the layers' internal data structures.
+ use nf, only: dense, input, layer, network
+ use nf_conv2d_layer, only: conv2d_layer
+ use nf_dense_layer, only: dense_layer
+
+ implicit none
+
+ type(network) :: net
+ integer :: n
+
+ net = network([input(3), dense(5), dense(2)])
+
+ do n = 1, size(net % layers)
+ print *, "Layer ", n, "is " // net % layers(n) % name
+ select type (this_layer => net % layers(n) % p)
+ type is (dense_layer) 
+ print *, " with weights of shape", shape(this_layer % weights)
+ print *, " and ", size(this_layer % biases), " biases"
+ print *, "Weights are:"
+ print *, this_layer % weights
+ type is (conv2d_layer)
+ print *, " with kernel of shape", shape(this_layer % kernel)
+ print *, " and ", size(this_layer % biases), " biases"
+ print *, "Kernel is:"
+ print *, this_layer % kernel
+ class default
+ print *, " with no parameters"
+ end select
+ end do
+
+end program network_parameters