I am assuming that you want to do this empirically : x0 <- 0.899 x <- c( rnorm(6000), rnorm(4000, mean=3) ) plot( d <- density(x) )
y0 <- approx( d$x, d$y, xout=x0 )$y # height at x0 segments( x0, 0, x0, y0, col=2 ) If you want a shaded effect, you can try the following : xx <- seq( x0, max(x), by=0.1 ) yy <- approx( d$x, d$y, xout=xx )$y plot(d) polygon( c( xx, rev(xx) ), c( yy, rep(0, length(yy)) ), col=8 ) On Thu, 2005-06-16 at 09:12 +0800, Hu Chen wrote: > Thanks. > A small arrow may be more nice-looking than a long cutting line. > and, another question, > how to get the p-value of the position of X0? > If the whole distribution is not as regular as norm, chi-square but a > strange one, how could I get the X0's p-value? > > any functions? > > Thanks very much. > > On 6/15/05, Jim Brennan <[EMAIL PROTECTED]> wrote: > > This is one way not so good > > R>X<-rnorm(1000000) > > R>X0<-.899 > > R>plot(density(X)) > > R>abline(v=X0) > > > > A better way > > > > R>x<-seq(-5,5,.01) > > R>plot(x,dnorm(x)) > > R>plot(x,dnorm(x),type="l",col=2) > > R>abline(v=X0,col=4) > > R>?text > > R>text(X0,.2,paste("P(X<X0) =",signif(pnorm(X0),3)),pos=2) > > R>abline(v=X0,col=4) > > > > If you actually want arrows do ?arrows > > Jim > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Hu Chen > > Sent: June 15, 2005 10:41 AM > > To: R > > Subject: [R] how to plot density distribution with a arrow pointer? > > > > Hi all, > > for example: > > > X<- rnorm(1000) > > > X0 <- 0.899 > > > > I want to draw a density distribution plot with a arrow pointer > > indicating the position of X0, meanwhile, giving out the p-value. > > > > any functions? > > > > Thanks very much. > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > > http://www.R-project.org/posting-guide.html > > > > > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html