Draws arrows on a map to indicate a coordinate system, e.g. for an to indicate a coordinate system set up so that one axis is parallel to a coastline.

mapCoordinateSystem(longitude, latitude, L = 100, phi = 0, ...)

Arguments

longitude

numeric vector of longitudes in degrees.

latitude

numeric vector of latitudes in degrees.

L

axis length in km.

phi

angle, in degrees counterclockwise, that the "x" axis makes to a line of latitude.

...

plotting arguments, passed to mapArrows(); see “Examples” for how to control the arrow-head size.

Details

This is a preliminary version of this function. It only works if the lines of constant latitude are horizontal on the plot.

See also

Examples

# \donttest{ library(oce) if (requireNamespace("ocedata", quietly=TRUE)) { data(coastlineWorldFine, package='ocedata') HfxLon <- -63.5752 HfxLat <- 44.6488 mapPlot(coastlineWorldFine, proj='+proj=merc', longitudelim=HfxLon+c(-2,2), latitudelim=HfxLat+c(-2,2), col='lightgrey') mapCoordinateSystem(HfxLon, HfxLat, phi=45, length=0.05) }
# }