#R user group targets package coding demo

library(targets)
library(tidyverse)
library(broom)


#1. Write some basic functions ------------------------

import <- function(raw_data) {mtcars}
clean <- function(imported_data) {filter(imported_data, mpg>20)}
model <- function(cleaned_data) {tidy(lm(mpg ~ wt, data=cleaned_data))}
visualise <- function(cleaned_data) {ggplot(aes(x=mpg, y=hp), data=cleaned_data) + geom_point() + geom_smooth()}


#2. Run with pipes -----------------------------------

import() %>% 
	clean() %>% 
	model()

import() %>% 
	clean() %>% 
	visualise()


#3. Replace the piped code with a targets pipeline ---------------------------

targets <- list(
	tar_target(imported_data, import()),
	tar_target(cleaned_data, clean(imported_data)),
	tar_target(model_data, model(cleaned_data)),
	tar_target(plots, visualise(cleaned_data))
)

#Run tar_visnetwork()
#Run tar_make()


#4 Change the clean function --------------------------------------

clean <- function(imported_data) {filter(imported_data, mpg>30)}

#Run tar_visnetwork()
#Run tar_make()
#Run tar_visnetwork()


#5 Change the model function, map()ing over formulas ----------------

model <- function(cleaned_data) {
	formulas <- c(
		"mpg ~ hp",
		"mpg ~ cyl",
		"mpg ~ drat")
	map(formulas, ~lm(.x, data=cleaned_data))
}

#Run tar_make()
#Run tar_visnetwork()


#6 Add models as branching pattern -----------------------------------

# Add a new formulas target to the targets pipeline
tar_target(formulas, c(
  "mpg ~ hp",
  "mpg ~ cyl",
  "mpg ~ drat"))

# Change the model function to take formulas as well as data
model <- function(cleaned_data, formulas) {tidy(lm(as.formula(formulas), data=cleaned_data))}

# Change the model_data target to include formula and pattern=formulas
tar_target(model_data, model(cleaned_data, formulas), pattern = formulas)

#Run tar_make()
#Run tar_visnetwork()


# 7 Change one formula in the formulas target -----------------------------------
tar_target(formulas, c(
		"mpg ~ wt",
		"mpg ~ cyl",
		"mpg ~ drat"))

#Run tar_visnetwork()
#Run tar_make()
#Run tar_visnetwork()