R/p_format.R

In shug0131/cctu: In-house Functions for Report Writing at Cambridge Clinical Trials Unit

#' formats p values with rounding and <0.001
#'
#' @param p vector of numeric p-values
#' @param digits the number of digits to round to, and define the threshold to use the < symbol
#'
#' @return character vector of formated p-values
#'
#' @examples
#'  p_format(c(0.000001,0.451234))
#' @export


p_format <- function(p, digits=3){
  # check input
  if(!is.numeric(p)){stop("'p_format' requires numeric input")}
  if(trunc(digits)!=digits){stop("'digits' argument must be an integer")}
  if( any(p<0) | any(1< p)){warning("p-values outside of the [0,1] range")}
  if( digits<1){warning("ouput is rounding to the left of the decimal point")}
# do the formatting
  threshold <- 10^(-digits)
  pchar <- round(p, digits=digits)
  fmt <- paste0("%1.",digits,"f")
  ifelse(p<threshold,
         paste0("<",threshold),
         paste0(" ",sprintf(fmt,pchar))
  )
}