R help - Jun 2004 - Is there an R-version of rayplot

I need to make plots similar to those produced by the s-plus rayplot function
but can't seem to find it in R.  These 'vector maps' plot a ray or
vector at each specified location. Is there something similar in R ?

--Rich

Richard Kittler 
AMD TDG
408-749-4099

>>>>> "richard" == richard kittler <richard.kittler
at amd.com>
>>>>>     on Tue, 8 Jun 2004 09:19:51 -0700 writes:
    richard> I need to make plots similar to those produced by
    richard> the s-plus rayplot function but can't seem to find
    richard> it in R.  These 'vector maps' plot a ray or vector
    richard> at each specified location. Is there something
    richard> similar in R ?  --Rich

Do 

   ?stars
   ?symbols

help further?
Also, maybe,
	par(ask = TRUE)
	example(stars)

Regards,
Martin Maechler

Thanks for this example.  I have since found the 'arrows' function which
is not as comprehensive as rayplot but seems to work well for basic vector field
plots, e.g.

 y <- rep(1:5,rep(5,5))  
 x <- rep(1:5,5)         

 x1 <- x-sqrt(x*x + y*y)/25
 y1 <- y-2*x/125

 plot(x,y,,main='Sample Vector Plot',type='n')
 arrows(x,y,x1,y1,length=0.1) 


--Rich

Richard Kittler 
AMD TDG
408-749-4099

-----Original Message-----
From: joerg van den hoff [mailto:j.van_den_hoff at fz-rossendorf.de] 
Sent: Wednesday, June 09, 2004 4:10 AM
Cc: Kittler, Richard; r-help at stat.math.ethz.ch
Subject: Re: [R] Is there an R-version of rayplot


maybe this q&d try helps?


#=================cut herer============
vectorplot <- function (field) {

   #input is a (N x 4 array) of N vectors:
   #   field[,1:2] - x/y position  of vectors
   #   field[,3:4] - x/y componnent of vectors
   # plotted are the 2-D vectors attached to  the specified positions

   if (is.null(dim(field))||dim(field)[2] != 4) stop("N x 4 array
expected")

   loc <- field[,1:2]
   val <- field[,3:4]

   alpha <- rbind(loc[,1],loc[,1]+val[,1])
   omega <- rbind(loc[,2],loc[,2]+val[,2])

   matplot(alpha,omega,type='l',lty=1,col='black') #the vector
lines
   points(loc) #the start points
   points(loc+val,pch=20) #the end points
}

#example:

loc=matrix(rnorm(100),50,2)
field <- cbind(loc,loc)
vectorplot(field)

#=================cut herer============
there are no nice arrow heads, of course, but one could construct some... for
now, vectors start with open circles and end with filled circles.

joerg