Locate points on an existing map.
mapLocator(n = 512, type = "n", ...)number of points to locate; see locator.
type of connector for the points; see locator.
This uses map2lonlat to infer the location in
geographical space; see the documentation for that function on its
limitations.
A map must first have been created with mapPlot.
Other functions related to maps: lonlat2map,
lonlat2utm, map2lonlat,
mapArrows, mapAxis,
mapContour,
mapDirectionField, mapGrid,
mapImage, mapLines,
mapLongitudeLatitudeXY,
mapPlot, mapPoints,
mapPolygon, mapScalebar,
mapText, mapTissot,
oceCRS, shiftLongitude,
usrLonLat, utm2lonlat