mapDirectionField {oce} | R Documentation |
Plot a direction field on a existing map
mapDirectionField(longitude, latitude, u, v, scale=1, length=0.05, code=2, col=par("fg"), ...)
longitude, latitude |
starting points for arrows |
u, v |
components of a vector to be shown as a direction field |
scale |
latitude degrees per unit of |
length |
length of arrow heads, passed to |
code |
code of arrows, passed to |
col |
colour of arrows. This may be a single colour, or a matrix
of colours of the same dimension as |
... |
optional arguments passed to |
Adds arrows for a direction field on an existing map. There are
different possibilities for how longitude
, latitude
and
u
and v
match up. In one common case, all four of these are
matrices, e.g. output from a numerical model. In another, longitude
and latitude
are the coordinates along the matrices, and are thus
stored in vectors with lengths that match appropriately.
Dan Kelley
See mapPlot
for general information on plotting maps,
including other functions.
## Not run: library(oce) data(coastlineWorld) par(mar=rep(2,4)) mapPlot(coastlineWorld, longitudelim=c(-120,-55), latitudelim=c(35,50), proj="lambert", parameters=c(lat0=40,lat1=60), orientation=c(90,-90,0)) lon <- seq(-120, -60, 15) lat <- 45 + seq(-15, 15, 5) lonm <- matrix(expand.grid(lon,lat)[,1], nrow=length(lon)) latm <- matrix(expand.grid(lon,lat)[,2], nrow=length(lon)) ## vectors pointed 45 degrees clockwise from north u <- matrix(1/sqrt(2), nrow=length(lon), ncol=length(lat)) v <- matrix(1/sqrt(2), nrow=length(lon), ncol=length(lat)) mapDirectionField(lon, lat, u, v, scale=3) mapDirectionField(lonm, latm, 0, 1, scale=3, col='red') # Color code by longitude, using thick lines col <- colormap(lonm)$zcol mapDirectionField(lonm, latm, 1, 0, scale=3, col=col, lwd=2) ## End(Not run)