On Tue, 6 Jul 2010, Michael Friendly wrote:
Michael Kubovy wrote:
Suppose we start with
data("Titanic")
mosaic(Titanic, shade = TRUE)
How do I combine the dashed box contours of shading_Friendly to indicate negative
residuals, with three levels of gray: dark for abs(Pearson Resid) > 4, lighter for 4
> abs(Pearson Resid) > 2, and lightest for bs(Pearson Resid) < 2 ?
Do you mean [1] you want to plot positive residuals in color and negative in
gray scale?
Or [2] to fold + and - residuals by shading all according to abs(resid), and
distinguishing + from - by the dashed box outlines?
In fact, I designed this coding scheme so that mosaic plots in color (with my
blue - white - red scheme) would approximately do exactly what
you might want under [2], when rendered in B/W, since the fully saturated red
and blue are close in darkness in B/W.
And shading_hcl() has been written to do exactly what you want under [2]. While
it is hard to come up with colors of different hues in HSV or HLS space that
have the same brightness (aka lightness/luminance) and the same
colorfulness (aka chroma), this is easy in HCL.
Try
mosaic(Titanic, gp=shading_Friendly)
save as a jpg/png and try converting to B/W with an image program and see if
this is good enough.
mosaic(Titanic, shade = TRUE)
is the same as
mosaic(Titanic, gp = shading_hcl)
which you can then modify to have different line types
mosaic(Titanic, gp = shading_hcl, gp_args = list(lty = 1:2))
If you print that on a grayscale printer you will see the same plot without any
chroma, i.e.,
mosaic(Titanic, gp = shading_hcl, gp_args = list(lty = 1:2, c = 0))
The shading_hcl() function is introduced in Zeileis et al. (2007, JCGS), see
?shading_hcl, which provides more detailed references to HCL colors etc.
Best,
Z
Alternatively, write your own, shading_Kubovy, modeled on
shading_Friendly <-
function (observed = NULL, residuals = NULL, expected = NULL,
df = NULL, h = c(2/3, 0), lty = 1:2, interpolate = c(2, 4),
eps = 0.01, line_col = "black", ...)
{
shading_hsv(observed = NULL, residuals = NULL, expected = NULL,
df = NULL, h = h, v = 1, lty = lty, interpolate = interpolate,
eps = eps, line_col = line_col, p.value = NA, ...)
}
<environment: namespace:vcd>
attr(,"class")
[1] "grapcon_generator"
In the defaults, lty=1:2 is what distinguishes + and - for outline line type
hope this helps,
-Michael
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