plotBoxes(obj, at, width, horizontal, col, add, label.levels, label.groups, orientation = "", ...)
par
help page."plotTs" and "plotBoxes" use traditional R graphics and will not be discussed further here.
"plotLetters" uses 'grid' graphics, because it seems to provide more support for controlling the side-by-side placement of "Letters" of possibly different colors and widths. The "Letters" display will be positioned in the "plot region" defined by fig and mar, assuming the entire device region is 37 lines both wide and tall. Thus, the plot region is diff(fig[1:2])*37 lines wide and diff(fig(1:2])*37 lines high. If, for example, fig = c(0.9, 1, 0, 1), this makes the plot region 3.7 lines wide. With the default mar=c(5, 4, 4, 2)+0.1 lines, the "width" of the plot region is therefore 3.7 - (4.1+2.1) = (-2.5) lines. "plotLetters" initially ignores this contradictory negative width, and centers the plot at the midpoint of h0 = fig[1]+mar[2]/37, h1 = fig[2]-mar[4]/37, v0 = fig[3]+mar[1]/37, and v1 = fig[4]-mar[3]/37. The "Letters" for the different levels compared are rescaled from at[, "center"] to fit inside At.rng = if(horizontal) c(h0, h1) else c(v0, v1). With "n" levels compared and at.rng = range(at[, "center"]), at[, "center"] is expanded to (at.rng+/-0.5) and rescaled to match At.rng; if(diff(At.rng)<=0), an="" error="" message="" is="" issued.<="" p="">
Meanwhile, the "Letters" are centered at the midpoint of W.rng = if(horizontal) c(v0, v1) else v(h0, h1) [the opposite of At.rng]; the argument "width" used by plotTs and plotBoxes is not used (and not even accepted) by plotLetters. If(label.levels), these are positioned in the midpoint of the right margin in the "W" direction.
=0),>plot.multcompTs
plot.multcompLetters
gpar
# Designed to be called from plot.multcompTs
# or plot.multcompLetters, NOT directly by users.
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