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
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