[R] Direction and scaling of cumulative distribution in ecdfplot

[Ken Knoblauch]

Jeff Stevens <stev0175 <at> googlemail.com> writes:
> I have two questions regarding the ecdfplot function in the
> latticeExtra package.
> 1. How can I plot the fraction of values >= x rather than <=x, like
> the what = "1-F" argument in the Ecdf function in the Hmisc package?
> 
> 2. When I try to log-transform the y-axis, I get a warning that it
> can't have log Y-scale, and it fails to scale properly:
> How can I log-transform the y-axis in ecdfplot?  Here is a test
> example of my analysis in R version 2.10.1 in Ubuntu 9.10:
> > resp <- c(0.23, 0.09, 0.05, 0.02, 0.38, 1, 0.04, 0.01, 0.17, 0.04, 0.01, 
0.17, 0.5)
> > id <- c(rep(1, 5), rep(2, 4), rep(3, 4))
> > testdata <- data.frame(id, resp)
> > ecdfplot(~resp | id, data = testdata, scales = list(x = list(relation = 
"free",
 log = TRUE),y = list(log =
> TRUE)), type = "p")
> Warning message:
> In densityplot.formula(x = ~resp | id, data = list(id = c(1, 1,  :
>   Can't have log Y-scale

If I understand what you are trying to do, I put this together
a while back (which was not optimal but it worked at the
time), but I haven't tested it since.

ecdflt <- function(x) {
	cdf <- as.vector(
	sapply(sort(x, decreasing = TRUE), 
              function(y) sum(x >= y)/length(x))
	)
	cbind(sort(x, decreasing = TRUE), cdf)
	}
	
panel.ecdflt <- function(x, logY = TRUE, ...) {
	xy <- ecdflt(x)
	if (logY) xy[, 2] <- log10(xy[, 2])
	panel.xyplot(xy[, 1], xy[, 2], ...)
	}

xyplot(X ~ X | F, panel = function(x, y = NULL, ...){
	panel.ecdflt(x, ...)
	})

> 
> Many thanks,
> Jeff
> 
> --
> Jeff Stevens
> Research Scientist
> Center for Adaptive Behavior and Cognition
> Max Planck Institute for Human Development
> Lentzealle 94
> 14195 Berlin, Germany
> 
-- 
Ken Knoblauch
Inserm U846
Stem-cell and Brain Research Institute
Department of Integrative Neurosciences
18 avenue du Doyen Lépine
69500 Bron
France
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