final_rework_of_dynamic_function.r

library(lubridate)
library(tidyverse)
library(rlang)

set.seed(123)

new_table <- tibble(
  Date = seq.Date(as.Date("2016-01-01"), as.Date("2019-12-31"), 1)) %>% 
  mutate(total_sales = rnorm(n()))


function_arguments <- c("dataset" = "new_table",
                        "date_col" = "Date",
                        "sales_col" = "total_sales")


new_yearly_lines_fn <- function(dataset, date_col, sales_col) {
 
  if (class(dataset) == "character") {
    dataset <- eval(sym(dataset)) }
  
  if (class(date_col) == "character") {
    date_col <- sym(date_col) } 
  else
    {date_col <- sym(quote(date_col))}
  
  if (class(sales_col) == "character") {
    sales_col <- sym(sales_col) } 
  else
    {sales_col <- sym(quote(sales_col))}
  


  dataset %>%
    group_by(year_month = floor_date({{date_col}}, "months"),
             year = year({{date_col}})) %>%
    summarise(total_sales = sum({{sales_col}})) %>%
    ungroup() %>%
    ggplot() +
    aes(year_month, total_sales, col = factor(year)) +
    geom_line(stat = "identity", size = 2) +
    geom_point(stat = "identity", size = 2, col = "black")

}



new_yearly_lines_fn(new_table, Date, total_sales)


new_yearly_lines_fn(function_arguments[["dataset"]], 
                    function_arguments[["date_col"]], 
                    function_arguments[["sales_col"]])