knitr::opts_chunk$set( collapse = TRUE, comment = "#>" )
Most models automatically included in finnts, including all multivariate models, have various hyperparameters with values that need to be chosen before a model is trained. Finn solves this by leveraging the tune package within the tidymodels ecosystem.
When prep_models()
is ran, hyperparameters and back test splits are calculated and written to disk. You can get the results by calling get_prepped_models()
.
library(finnts) hist_data <- timetk::m4_monthly %>% dplyr::filter( date >= "2012-01-01", id == "M2" ) %>% dplyr::rename(Date = date) %>% dplyr::mutate(id = as.character(id)) run_info <- set_run_info( experiment_name = "finnts_fcst", run_name = "get_prepped_models" ) prep_data( run_info = run_info, input_data = hist_data, combo_variables = c("id"), target_variable = "value", date_type = "month", recipes_to_run = "R1", forecast_horizon = 6 ) prep_models( run_info = run_info, models_to_run = c("arima", "ets", "xgboost"), num_hyperparameters = 10 ) model_info <- get_prepped_models(run_info = run_info) back_test_info <- model_info %>% dplyr::filter(Type == "Train_Test_Splits") %>% dplyr::select(Data) %>% tidyr::unnest(Data) print(back_test_info) print(unique(back_test_info$Run_Type)) model_workflow_info <- model_info %>% dplyr::filter(Type == "Model_Workflows") %>% dplyr::select(Data) %>% tidyr::unnest(Data) print(model_workflow_info) model_hyperparameter_info <- model_info %>% dplyr::filter(Type == "Model_Hyperparameters") %>% dplyr::select(Data) %>% tidyr::unnest(Data) print(model_hyperparameter_info)
The above outputs allow a Finn user to understand what hyperparameters are chosen for tuning and how the model refitting process will work. When tuning hyperparameters, Finn uses the "Validation" train/test splits, with the final parameters chosen using RMSE. For some models like ARIMA that don't follow a traditional hyperparameter tuning process, the model is fit from scratch across all train/test splits. After hyperparameters are chosen, the model is refit across the "Back_Test" and "Future_Forecast" splits. The "Back_Test" splits are the true testing data that will be used when selecting the final "Best-Model". "Ensemble" splits are also created as ensemble training data if ensemble models are chosen to run. Ensemble models follow a similar tuning process.
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