ylimFromXlim: Adjust ylim to xlim

Description

This simple function is useful for adjusting x and y coordinate ranges xlim and ylim in order to maintain a desired display ratio. The former must be given, the latter will be adjusted.

Usage

ylimFromXlim(xlim, centerY = 0, x_to_y = 16/9)

Value

A numeric vector of length 2; the lower and upper boundary of the resulting vertical coordinate range

Arguments

xlim: Numeric vector of length 2; the fixed lower and upper boundary of the horizontal coordinate range
centerY: The vertical coordinate which the output range is to be centered around (default = 0)
x_to_y: The desired ratio of the horizontal (x) to the vertical (y) range. Default is 16/9, a display ratio frequently used for computer or mobile screens

Details

For certain purposes, e.g. producing a graph that exactly matches a screen, the x and y coordinates must be adjusted to match a given display ratio. If the horizontal range, xlim, the desired ratio, x_to_y and the desired center of the y-range, centerY are provided, this function returns an adapted vertical range, that can be used as ylim in any plot including phasePortrait.

Examples

Run this code

# Make a phase portrait of a Jacobi theta function that fully covers a
# plot with a display aspect ratio of 4/3.
# 10 inch wide window with 4/3 display ratio (x/y)
# \donttest{
# x11(width = 10, height = 10 * 3/4) # Screen device commented out
                                     # due to CRAN test requirements.
                                     # Use it when trying this example
xlim <- c(-3, 3)
ylim <- ylimFromXlim(xlim, centerY = -0.3, x_to_y = 4/3)
op <- par(mar = c(0, 0, 0, 0), bg = "black") # Omit all plot margins
phasePortrait(jacobiTheta, moreArgs = list(tau = 1i/2 - 1/3),
  xlim = xlim, ylim = ylim, # Apply the coordinate ranges
  xaxs = "i", yaxs = "i",   # Allow for now room between plot and axes
  nCores = 1) # Max. two cores allowed on CRAN
              # not a limit for your own use
par(op)
  # \dontshow{
  # R CMD check: make sure any open connections are closed afterward
  foreach::registerDoSEQ()
  doParallel::stopImplicitCluster()
  # }
# }