R/getTicks.R

In raredd/Gmisc0: Collection of functions for plotting relations, generating tables, and more.

#' Ticks for plot axis
#'
#' Gets the ticks in a formatted version. This is since I'm not always
#' that fond of just pretty(1:10/5). In exponential form the ticks are
#' determined from the 2-base, meaning that you get an intuitive feeling
#' for when the value is doubled.
#'
#' This function is far from perfect and I recommend specifying yourself
#' the ticks that you want.
#'
#' @param low lower bound, can be a single number or a vector
#' @param high upper bound - optional, you can just have all data in the low variable
#' @param clip if the ci are clipped
#' @param exp If the value should be in exponential form (default)
#' @param digits Number of digits - used in exp mode
#' @return \code{vector} Returns a vector with the ticks
#'
#' @example inst/examples/getTicks_example.R
#' @export
getTicks <- function(low,
  high = low,
  clip = c(-Inf, Inf),
  exp = FALSE,
  digits = 0){

  # Get the right ticks
  lowest <- max(min(low, na.rm=TRUE), clip[1])
  bottom <- floor(lowest*2)/2
  if (bottom == 0 & exp){
    bottom <- 2^(round(log2(lowest)*2)/2)
  }

  highest <- min(max(high, na.rm=TRUE), clip[2])
  roof <- ceiling(highest*2)/2
  if (exp == FALSE){
    resolution <- roof-bottom

    if (resolution > 20){
      bottom <- floor(bottom)
      roof <- ceiling(roof)
      xticks <- seq(from=bottom, to=roof, by=10^floor(log10(resolution))/4)
    }else if (resolution > 6){
      bottom <- floor(bottom)
      roof <- ceiling(roof)
      xticks <- seq(from=bottom, to=roof, by=1)
    }else if(resolution <= 1){
      decimals <- -ceiling(log10(resolution))+1
      bottom <- floor(lowest*2*10^decimals)/2/10^decimals
      roof <- ceiling(highest*2*10^decimals)/2/10^decimals
      xticks <- seq(from=bottom, to=roof, by=10^-decimals/4)
      if (length(xticks) <= 3)
        xticks <- seq(from=bottom, to=roof, by=10^-decimals/8)
    }else{
      bottom <- floor(bottom*2)/2
      roof <- ceiling(roof*2)/2
      xticks <- seq(from=bottom, to=roof, by=.5)
    }

    if (!bottom %in% xticks)
      xticks <- c(bottom, xticks)
    if (!roof %in% xticks)
      xticks <- c(xticks, roof)
  }else{
    if (bottom <= 0)
      stop("You can't have an exponential scale that goes <= 0, bottom = '", bottom, "'")

    xticks <- c()
    increase_by <- 1
    if (abs(bottom-roof) < 3){
      # A regular log. scale wont really work :-(
      #return(seq(from=bottom, to=roof, by=0.5))
      increase_by <- 0.5
    }

    if (bottom < 1)
      xticks <- append(xticks, round(rev(2^seq(from=0, to=log2(bottom), by=-increase_by)), digits+1))

    if (roof > 1)
      xticks <- unique(append(xticks, round(2^seq(from=0, to=log2(roof), by=increase_by), digits)))
  }

  # Choose the one thats numberwise the closest
  if (abs(lowest-xticks[1]) >= abs(lowest-xticks[2]))
    xticks <- xticks[-1]

  if (abs(highest-xticks[length(xticks)]) >= abs(highest-xticks[length(xticks)-1]))
    xticks <- xticks[-length(xticks)]

  return(xticks)
}