R/even_lims.R

In ryan-heslin/matador: Linear Algebra Visualization

#' Set Even Limits Based on Data Values
#' @description This function takes a numeric vector and returns a range of the negative and positive of the element with the highest absolute
#' value. The lower bound is rounded down to the next integer, the upper bound rounded up.
#'  It is intended to set even limits on plots when called on the breaks or data values corresponding to an aesthetic,
#'  and usefully always returns an interval containing 0.
#' @param vec A vector, typically a row or column representing a dimension to plot
#'
#' @return A length 2 vector consisting of the negative and positive of the value of @param vec
#' with the greatest absolute value,
#' respectively rounded down and up.
#' @export
#'
#' @examples
#' # Create four-quadrant plot
#' library(ggplot2)
#'
#`p <- ggplot(mtcars, aes(x = hp, y = mpg)) +
#`  geom_point()+
#`  scale_x_continuous(limits = even_lims)+
#`  scale_y_continuous(limits = even_lims)
#`p
#`p + make_axes(p)
even_lims <- function(vec) {

  thresh <- max(abs(vec))
  c(floor(-thresh), ceiling(thresh))

}