## ----include = FALSE----------------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  eval = FALSE
)

## ----setup--------------------------------------------------------------------
# library(torch)
# library(luz)

## -----------------------------------------------------------------------------
# net <- nn_module(
#   "Net",
#   initialize = function() {
#     self$fc1 <- nn_linear(100, 50)
#     self$fc1 <- nn_linear(50, 10)
#   },
#   forward = function(x) {
#     x %>%
#       self$fc1() %>%
#       nnf_relu() %>%
#       self$fc2()
#   }
# )

## -----------------------------------------------------------------------------
# fitted <- net %>%
#   setup(
#     loss = nn_cross_entropy_loss(),
#     optimizer = optim_adam,
#     metrics = list(
#       luz_metric_accuracy
#     )
#   ) %>%
#   fit(train_dl, epochs = 10, valid_data = test_dl)

## -----------------------------------------------------------------------------
# net <- nn_module(
#   "Net",
#   initialize = function() {
#     self$fc1 <- nn_linear(100, 50)
#     self$fc1 <- nn_linear(50, 10)
#   },
#   forward = function(x) {
#     x %>%
#       self$fc1() %>%
#       nnf_relu() %>%
#       self$fc2()
#   },
#   set_optimizers = function(lr_fc1 = 0.1, lr_fc2 = 0.01) {
#     list(
#       opt_fc1 = optim_adam(self$fc1$parameters, lr = lr_fc1),
#       opt_fc2 = optim_adam(self$fc2$parameters, lr = lr_fc2)
#     )
#   },
#   loss = function(input, target) {
#     pred <- ctx$model(input)
# 
#     if (ctx$opt_name == "opt_fc1")
#       nnf_cross_entropy(pred, target) + torch_norm(self$fc1$weight, p = 1)
#     else if (ctx$opt_name == "opt_fc2")
#       nnf_cross_entropy(pred, target)
#   }
# )

## -----------------------------------------------------------------------------
# fitted <- net %>%
#   setup(metrics = list(luz_metric_accuracy)) %>%
#   fit(train_dl, epochs = 10, valid_data = test_dl)

## -----------------------------------------------------------------------------
# net <- nn_module(
#   "Net",
#   initialize = function() {
#     self$fc1 <- nn_linear(100, 50)
#     self$fc1 <- nn_linear(50, 10)
#   },
#   forward = function(x) {
#     x %>%
#       self$fc1() %>%
#       nnf_relu() %>%
#       self$fc2()
#   },
#   set_optimizers = function(lr_fc1 = 0.1, lr_fc2 = 0.01) {
#     list(
#       opt_fc1 = optim_adam(self$fc1$parameters, lr = lr_fc1),
#       opt_fc2 = optim_adam(self$fc2$parameters, lr = lr_fc2)
#     )
#   },
#   step = function() {
#     ctx$loss <- list()
#     for (opt_name in names(ctx$optimizers)) {
# 
#       ctx$pred <- ctx$model(ctx$input)
#       opt <- ctx$optimizers[[opt_name]]
#       loss <- nnf_cross_entropy(pred, target)
# 
#       if (opt_name == "opt_fc1") {
#         # we have L1 regularization in layer 1
#         loss <- nnf_cross_entropy(pred, target) +
#           torch_norm(self$fc1$weight, p = 1)
#       }
# 
#       if (ctx$training) {
#         opt$zero_grad()
#         loss$backward()
#         opt$step()
#       }
# 
#       ctx$loss[[opt_name]] <- loss$detach()
#     }
#   }
# )