vectorField {plotrix} | R Documentation |
Display magnitude/direction vectors as arrows on an existing plot.
vectorField(u,v,xpos=NA,ypos=NA,scale=1,headspan=0.1, vecspec=c("lonlat","rad","deg"))
u,v |
x (longitude) and y (latitude) offsets OR orientation and magnitude in either radians or degrees. See details. |
xpos,ypos |
The centers of the vectors in user units. |
scale |
The proportion of each cell that the maximal vector will fill. See details. |
headspan |
The extent of the heads of the arrows as a proportion of cell size. |
vecspec |
How the vectors are described. See details |
vectorField
displays arrows on an existing plot. Each arrow is specified
by a position on the plot xpos,ypos
and either x/y offsets or
orientation and magnitude. The default is x/y offsets, and the user must
specify whether radians or degrees are used if the orientation/magnitude option
is used.
If the first four arguments are matrices, there must be no missing values. If these arguments are vectors, the calculation of the scaling of the magnitudes and length of the arrowheads may be slightly different.
nil
Jim Lemon (original code by Robin Hankin and Brian Ripley)
# this requires the maps package if(suppressPackageStartupMessages(require(maps))) { map("world",xlim=c(110,155),ylim=c(-40,-10)) par(xpd=TRUE) text(132,-5,"Approximate magnetic deviation - Australia",cex=1.5) par(xpd=FALSE) long<-rep(seq(117.5,152.5,by=5),6) lat<-rep(c(-12.5,-17.5,-22.5,-27.5,-32.5,-37.5),each=8) # just show the direction, don't have a magnitude difference mag<-rep(1,48) devdeg<-c(110,98,85,65,65,65,65,65, 115,100,90,80,72,66,63,55, 130,100,90,82,72,67,62,54, 122,111,95,86,70,67,56,48, 118,116,110,87,74,68,62,45, 128,115,107,90,78,66,53,45) vectorField(devdeg,mag,long,lat,scale=0.7,vecspec="deg") }