mapDirectionField | 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 |
numeric vectors of the starting points for arrows. |
u, v |
numeric vectors of the 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 |
color of arrows. This may be a single color, or a matrix
of colors 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
A map must first have been created with mapPlot()
.
Other functions related to maps:
formatPosition()
,
lonlat2map()
,
lonlat2utm()
,
map2lonlat()
,
mapArrows()
,
mapAxis()
,
mapContour()
,
mapCoordinateSystem()
,
mapGrid()
,
mapImage()
,
mapLines()
,
mapLocator()
,
mapLongitudeLatitudeXY()
,
mapPlot()
,
mapPoints()
,
mapPolygon()
,
mapScalebar()
,
mapText()
,
mapTissot()
,
oceCRS()
,
shiftLongitude()
,
usrLonLat()
,
utm2lonlat()
## Not run:
library(oce)
data(coastlineWorld)
par(mar=rep(2, 4))
mapPlot(coastlineWorld, longitudelim=c(-120,-55), latitudelim=c(35, 50),
projection="+proj=laea +lat0=40 +lat1=60 +lon_0=-110")
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)
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