Assert column types

[FlukeAndFeather]

It would be great to assert column types as well as names. E.g. something like

assertable::assert_coltypes(data, c(a = numeric(0), b = character(0)))

[gnguy]

Thanks for the suggestion -- to have this be as flexible as possible for different conditions, I could see this looking something like this:

data <- data.table(a = c(1:3), b = c("a", "b", "c"))
assert_coltypes(data, list(a = is.numeric, b = is.character))

assert_coltypes <- function(data, col_list) {
  message_list <- c()
  for(col_name in names(col_list)) {
    col_function<- col_list[[col_name]]
    if(!col_function(data[[col_name]])) {
      message_list <- c(message_list, paste(col_name, "failed", deparse(substitute(col_function)), "assertion"))
     }
  }
  if(length(message_list) > 0) stop(paste(message_list, collapse = ", "))
}

The display of the functions on the failure condition isn't ideal, so it would require some work to figure out how to make that part a bit cleaner. But otherwise seems feasible.

[gnguy]

I'm a bit tight for time in the upcoming weeks -- if you have time and ability to add something based on the above, feel free to go for it. Otherwise I can take a stab in a month or so.