R/archive/num_result.R

In sigbertklinke/exams2moodle: Access routines to XML Moodle files and helper routines to simplify generating exercises for Moodle from the 'exams' package

#' num_result
#'
#' `num_result` creates a list with the elements
#' 
#' * `x` the original values
#' * `fx` the rounded values with [exams::fmt()] as character
#' * `tolerance` the tolerance
#' * `digits` the digits used for rounding
#' 
#' Note that `x` may contain more than one numeric value to determine the rounding and tolerance. 
#' Make sure that you use for numeric exercises `...$x[1]`.
#' 
#' If `digits` are not given and `length(x)>1` then `ceiling(-log10(min(diff(sort(x)), na.rm=TRUE)))` is used.
#' If `digits` are not given and `length(x)==1` then `3+ceiling(-log10(abs(x)))` is used.
#' If no `tolerance` is given then `tolmult*10^(1-digits)` is used.
#' 
#' `int_result` can be used if the result is an integer number and calls `num_result(x, 0, 0.1, 1, ...)` with 
#' a tolerance of 0.1.
#' 
#' @param x numeric: rounded data
#' @param digits numeric: number of digits to rounding (default: \code{NULL})
#' @param tolerance numeric: tolerance for rounded data (default: \code{NULL})
#' @param tolmult numeric: mutiplier for tolerance 
#' @param ... further parameters to [exams::fmt()]
#' 
#' @return a list
#' @md
#' @importFrom exams fmt
#' @export
#'
#' @examples
#' # height for german man (in meter)
#' x <- rnorm(10, mean=1.8, sd =0.25)
#' num_result(c(mean(x), x), digits=2)
#' int_result(mean(x))
#' #
#' str(num_result(pi, 3))
#' str(num_result(pi, 6))
#' str(num_result(pi, 6, tolmult=5))
#' str(num_result(pi, 6, tolmult=5, tolerance=1e-6))
num_result <- function(x, digits=NULL, tolerance=NULL, tolmult = 2, ...) {
  if (length(x)<2) {
    if (is.null(digits)) digits <- 4
    if ((x<0) || (x>0)) digits <- 3+ceiling(-log10(abs(x))) 
  } else {
    if (is.null(digits)) {
      digits <- ceiling(-log10(min(diff(sort(x)), na.rm=TRUE)))
    } 
  }
  tolerance <- if (is.null(tolerance)) tolmult*10^(1-digits) else tolmult*tolerance
  list(x=x, fx=fmt(x, digits=digits, ...), tolerance=tolerance, digits=digits)
}

#' @rdname num_result
#' @export
int_result <- function(x, ...) { num_result(as.integer(x), digits=0, tolerance=0.1, tolmult=1, ...) }