Finally I got the unreasonable contour plotted.
   
  http://www.geocities.com/useebi/data/kdecontour.jpeg
   
  The codes to get the plot,
   
  cdplot2d(survived ~ age + sibsp, data = titanic3)
   
  are in http://www.geocities.com/useebi/data/cdplot2d.txt
   
  One step that I couldn't accomplish as in cdplot is to eliminate those undefined conditional densities outside the ranges of the two covariates.  The plot dosen't make sense for areas with no x and y observation.  Probably, this is why the goal did not sound like anything reasonable.
   
  Anyway, I guess the naked eyes are pretty good to estimate the conditional density from the color coded scatterplot if nothing else works!
   
  marco
    

Deepayan Sarkar <deepayan.sarkar@gmail.com> wrote:
  On 10/25/06, Marco LO wrote:
> OK!
>
> # The R codes to generate the Trellis plot are from the R help archive by
> Karl Ove Hufthammer
>
> panel.estcontplot <- function(x, y, ..., pretty=TRUE, region=FALSE)
> {
> cest.gr=kde2d(x, y)
> cest.gr.lat=con2tr(cest.gr)
> panel.contourplot(cest.gr.lat$x, cest.gr.lat$y, cest.gr.lat$z,
> subscripts = seq(nrow(cest.gr.lat)),
> pretty=pretty, region=region, contour=TRUE, ...)
> }
>
> # The titanic3 dataset is from
> http://biostat.mc.vanderbilt.edu/twiki/pub/Main/DataSets/titanic3.xls
> with missing value imputations according to the book
>
> library(Hmisc)
> set.seed(17)
> xtrans <- transcan(~ I(age) + pclass + sex + sibsp + parch + survived, data
> = titanic3,
> n.impute=5, pl=F, trantab=T, imputed=T, transformed=TRUE)
> titanic3[ ,'age'] <- xtrans$transformed[ ,'age']
> titanic3[ ,'survived'] <- as.factor(titanic[ ,'survived'])
>
> library(lattice)
> xyplot(age ~ sibsp | survived, data = titanic3, panel=panel.estcontplot)
>
>
> Anyway, I realized that Trellis could only be conditional on the categorical
> variable while what I really want is conditional density plot of survived on
> the two covariates.

That goal does not sound like anything reasonable to me, but I don't
know much about categorical data analysis, so I'll let someone else
answer. However, based on your first post where you implied that you
expected 'densities' to 'add up to 1', I _will_ suggest this: if the
phrase "counting measure" does not mean anything to you, you should
seriously consider consulting a local statistician to whom it does.

-Deepayan


 		
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