Hello, Try the following. (i've changed the color of the first ecdf.)
loga <- log10(a+1) # do this logb <- log10(b+1) # only once f.a <- ecdf(loga) f.b <- ecdf(logb) # (2) max distance D x <- seq(min(loga, logb), max(loga, logb), length.out=length(loga)) x0 <- x[which( abs(f.a(x) - f.b(x)) == max(abs(f.a(x) - f.b(x))) )] y0 <- f.a(x0) y1 <- f.b(x0) plot(f.a, verticals=TRUE, do.points=FALSE, col="blue") plot(f.b, verticals=TRUE, do.points=FALSE, col="green", add=TRUE) ## alternatine, use standard R plot of ecdf #plot(f.a, col="blue") #lines(f.b, col="green") points(c(x0, x0), c(y0, y1), pch=16, col="red") segments(x0, y0, x0, y1, col="red", lty="dotted") ## alternative, down to x axis #segments(x0, 0, x0, y1, col="red", lty="dotted") Hope this helps, Rui Barradas maxbre wrote > > Hi all, > > given this example > > #start > > a<-c(0,70,50,100,70,650,1300,6900,1780,4930,1120,700,190,940, > > 760,100,300,36270,5610,249680,1760,4040,164890,17230,75140,1870,22380,5890,2430) > > length(a) > > b<-c(0,0,10,30,50,440,1000,140,70,90,60,60,20,90,180,30,90, > 3220,490,20790,290,740,5350,940,3910,0,640,850,260) > length(b) > > out<-ks.test(log10(a+1),log10(b+1)) > > # max distance D > out$statistic > > f.a<-ecdf(log10(a+1)) > f.b<-ecdf(log10(b+1)) > > plot(f.a, verticals=TRUE, do.points=FALSE, col="red") > plot(f.b, verticals=TRUE, do.points=FALSE, col="green", add=TRUE) > > #inverse of ecdf a > x.a<-get("x", environment(f.a)) > y.a<-get("y", environment(f.a)) > > # inverse of ecdf b > x.b<-get("x", environment(f.b)) > y.b<-get("y", environment(f.b)) > > > #end > > I want to plot the max distance between the two ecdf curves as in the > above given chart > > Is that possible and how? > > > Thanks for your help > > PS: this is an amended version of a previous thread (but no reply > followed) that I’ve deleted from Nabble repository because I realised it > was not enough clear (now I hope it’s a little better, sorry for that) > -- View this message in context: http://r.789695.n4.nabble.com/Kolmogorov-Smirnov-test-and-the-plot-of-max-distance-between-two-ecdf-curves-tp4631437p4631438.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.