From: Adaikalavan Ramasamy <ramasamy_at_cancer.org.uk>

Date: Thu 16 Jun 2005 - 16:55:59 EST

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 Received on Thu Jun 16 17:05:51 2005

Date: Thu 16 Jun 2005 - 16:55:59 EST

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 <jfbrennan@rogers.com> 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: r-help-bounces@stat.math.ethz.ch
**> > [mailto:r-help-bounces@stat.math.ethz.ch] 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 Received on Thu Jun 16 17:05:51 2005

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