Auxiliary function for constructing viewports for 1d and 2d (default) plots.
vport(ispace, xlim = NULL, ylim = NULL, x = NULL, y = NULL, ...)The viewport.
inner space (in \([0,1]\)))
x-axis limits; if  NULL, the data limits are used.
y-axis limits; if  NULL, the data limits are used.
x data (only used if is.null(xlim));
if NULL, 0:1 is used.
y data (only used if is.null(ylim)); if NULL, 0:1 is used.
additional arguments passed to the underlying viewport().
Marius Hofert
This is an auxiliary function used by the provided grid-related 1d and 2d plots.
Other graphical tools: 
l_ispace_config(),
na_omit_loon(),
plot_region(),
zenarrow()