[R] Gray level mosaic plot with shading_Friendly

[Michael Kubovy]

Dear Achim and Michael,

Thank you so much. Indeed, mosaic(Titanic, gp = shading_hcl, gp_args = list(lty = 1:2, c = 0)) does almost what I was looking for, except that for consistency and clarity, I would have expected the negative values on the legend to be be outlined with lty = 2.

Michael


On Jul 7, 2010, at 2:13 AM, Achim Zeileis wrote:

> 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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