## ----setup, include=FALSE-----------------------------------------------------
knitr::opts_chunk$set(echo = TRUE)

## ----eval=FALSE---------------------------------------------------------------
# fcs <- feature_columns(column_numeric("drat"))
# input <- input_fn(mtcars, response = "mpg", features = c("drat", "cyl"), batch_size = 8L)
# lr <- linear_regressor(
#   feature_columns = fcs
# ) %>% train(
#   input_fn = input,
#   steps = 2,
#   hooks = list(
#     hook_progress_bar()
#   ))

## ----eval=FALSE---------------------------------------------------------------
# lr <- linear_regressor(feature_columns = fcs)
# training_history <- train(
#   lr,
#   input_fn = input,
#   steps = 4,
#   hooks = list(
#     hook_history_saver(every_n_step = 2)
#   ))

## ----eval=FALSE---------------------------------------------------------------
# mean_losses_history <<- NULL
# hook_history_saver_custom <- function(every_n_step) {
# 
#     iter_count <<- 0
# 
#     session_run_hook(
# 
#       before_run = function(context) {
#         session_run_args(
#           losses = context$session$graph$get_collection("losses")
#         )
#       },
# 
#       after_run = function(context, values) {
#         iter_count <<- iter_count + 1
#         print(paste0("Running step: ", iter_count))
#         if (iter_count %% every_n_step == 0) {
#           raw_losses <- values$results$losses[[1]]
#           mean_losses_history <<- c(mean_losses_history, mean(raw_losses))
#         }
#       }
#     )
# }

## ----eval=FALSE---------------------------------------------------------------
# lr <- linear_regressor(
#   feature_columns = fcs
# ) %>% train(
#   input_fn = input,
#   steps = 4,
#   hooks = list(
#     hook_history_saver_custom(every_n_step = 1)
#   ))