[R] roc and lattice

From: rhk <mailing-lists_at_rhkoning.com>
Date: Wed 10 Jan 2007 - 07:31:54 GMT

Hello, I am afraid I do not fully understand all intricacies of programming in lattice plots. In the code below I try to plot an ROC curve, following R-news 4(1). When I condition on the variable 'group' I get the error message below, when I plot the curve for all data (i.e., y ~ pred.prob), I get the plot I want. Can someone point out why conditioning gives that message? Thanks, Ruud

> plot.a <- xyplot(y ~ pred.prob|group, data=x.df,

+  xlim=c(0,1),xlab="1-specificiteit",
+  ylab="sensitiviteit",
+  panel=function(x,y,subscripts,...){
+   DD <- table(-x,y)
+   sens <- cumsum(DD[,2])/sum(DD[,2])
+   mspec <- cumsum(DD[,1])/sum(DD[,1])
+   panel.xyplot(mspec,sens,type="l",...)
+   panel.abline(0,1)
+  })

> print(plot.a)

Error in panel(x = c(0.000265710002003069, 0.000345712857778025, 0.000265710002003069, :

        subscript out of bounds

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