newdata helper

[m-muecke]

newdata helper function to generate new data analogous to https://tsibble.tidyverts.org/reference/new-data.html
Other references: https://github.com/poissonconsulting/newdata

[m-muecke]

Like in the readme could look for very simple cases something like the following. Note this currently only works with order column, but not with key column:

library(checkmate)

generate_newdata = function(task, n = 1L, resolution = "day") {
  assert_count(n)
  assert_string(resolution)
  assert_choice(
    resolution, c("second", "minute", "hour", "day", "week", "month", "quarter", "year")
  )

  order_cols = task$col_roles$order
  target = task$target_names
  max_index = max(task$data(cols = order_cols)[[1L]])

  unit = switch(resolution,
    second = "sec",
    minute = "min",
    hour = ,
    day = ,
    week = ,
    month = ,
    quarter = ,
    year = identity(resolution),
    stopf("Invalid resolution")
  )
  unit = sprintf("1 %s", unit)
  index = seq(max_index, length.out = n + 1L, by = unit)
  index = index[2:length(index)]

  newdata = data.table(index = index, target = rep(NA_real_, n))
  setnames(newdata, c(order_cols, target))
  setDF(newdata)[]
}