Adds Labeled Midline and (Unlabeled) Lines or Shaded Regions Showing Plot Scaling to Trellis Panels.
panel.addScales(
scaleline = c(0,0),
scaleType = c("line", "region"),
ndig.midline = c(h = 2, v = 2),
col.midline = "red",
adj.midline = c(-0.1, -0.25),
midline.aes = list(lwd = if(colCode == "n") 1.5 else 3),
midline.label.aes =list(
col = if(colCode == "n")col.midline else "black",
fontface = "bold",
cex = .8),
scaleline.aes = list(lty = "dashed", col = "purple"),
region.aes = list(fill = "tan", alpha = .20),
colCode = c("n", "m", "r"),
palette = hcl.colors(n = 100, "Viridis"),
…
)A numeric vector of length 1 or 2 giving the distance from the scalelines to the midline(s); or equivalently, the half width(s) of the shaded scale regions. Signs are ignored. If two values are given, the first is the (vertical) distance to the horizontal midline and the second is the (horizontal) distance to the vertical midline. If a single value is given,it is assumed to be the first and the second is 0. 0 or NA mean: don't add that scaleline/region and midline.
Whether the scale distance from the midline is shown by scale lines or as a shaded region. Note: Use of shaded regions requires that the graphics device support alpha transparency. Regions will not be shown properly -- or at all -- if it does not.
Named or unnamed pair of integer arguments, or a single integer that will be replicated. The names must be (and are assumed to be if unnamed) "h" and "v" in that order and give the number of significant digits to show in the midline labels for the corresponding midlines. Non-integer values are rounded to integer, and values outside the range of 0 to 15digits are converted to 2. However, see the Details section below for a caveat.
Midline color. Can be given in any form suitable for the base col
parameter of par.
numeric: The adj vector of length two that will be fed to panel.text
to position the midline label with respect to the midline. c(.5,.5) centers
the label on the midline and lower limit of the relevant axis
(x-axis for a horizontal midline, so left-center; and y-axis for a vertical
midline, so bottom-center). See the base text function for details.
List of aesthetics of midline: lwd, lty, alpha, but
not col, as this is already specified in the
col.midline argument.
List of aesthetics of the midline label: col, cex, font,
fontface, etc., but not adj, as this is handled by
adj.midline. See panel.text for argument details.
List of aesthetics of the scale lines. Same as for
midline.aes except that col can be specified.
fill and alpha parameters for shaded scale region.
character: Should the midlines and possibly also the scale
regions be color coded by the midline value in the range of all midline values?
Doing this in addition to labeling their values can improve visual comparison
of midline levels among the panels. "m" means color code just the midlines; "r" means
color code both midlines and scale regions; "n", the default, means do not color code.
A vector of colors to use for color coding from low to high values.
See heat.colors for how to conveniently specify color palettes.
Additional arguments passed down to the panel function, mostly ignored here. But see the note below for an exception.
No value is returned. This panel function is added to the existing panel
function component of the trellis object on which addScales
dispatches. It adds midline(s) and scale lines or regions to the panels
when they are plotted.
Midline values with significant digits that change precision by
“small” amounts relative to the scaleline values are
zapped by the zapsmall() function to remove extra
digits in the display to improve readability. For example,
a midline value of 1.23 would be shown as 1 when
ndig.midline = 2 and scaleline = 100.