Display magnitude/direction vectors
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"),col=par("fg"))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 |
col |
Color(s) for the arrows. |
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.
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Jim Lemon (original code by Robin Hankin and Brian Ripley)
## Not run:
# this requires the maps package, and just wouldn't pass check
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")
## End(Not run)
# do a magnitude/direction plot with radians
plot(1:10,type="n",main="Random vectors")
mag<-runif(100)+1
dir<-runif(100)*2*pi
xpos<-rep(1:10,10)
ypos<-rep(1:10,each=10)
vectorcol<-sample(colors(),100)
vectorField(dir,mag,xpos,ypos,scale=0.8,vecspec="rad",col=vectorcol)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.