Draw Geographical Maps
Draw lines and polygons as specified by a map database.
map(database, regions) # simple form map(database = "world", regions = ".", exact = FALSE, boundary = TRUE, interior = TRUE, projection = "", parameters = NULL, orientation = NULL, fill = FALSE, color = 1, plot = TRUE, add = FALSE, namesonly = FALSE, xlim = NULL, ylim = NULL, wrap = FALSE, resolution = 1, type = "l", bg, mar, ...)
- character string naming a geographical database, or a list of
namesobtained from a previous call to
map. The string choices include a
- character vector that names the polygons to draw. Each database is composed of a collection of polygons, and each polygon has a unique name. When a region is composed of more than one polygon, the individual polygons have the name of the r
TRUE, only exact matches with
regionsare selected for drawing. If
FALSE, each element of
regionsis matched as a regular expression against the polygon names in the database and all m
FALSE, boundary segments are not drawn. A boundary segment is a line segment of the map that bounds only one of the polygons to be drawn. This argument is ignored if
FALSE, interior segments are not drawn. An interior segment is a line segment of the map that bounds two of the polygons to be drawn. This argument is ignored if
- character string that names a map projection to use.
mapprojlibrary). The default is to use a rectangular projection with the aspect ratio chos
- numeric vector of parameters for use with the
projectionargument. This argument is optional only in the sense that certain projections do not require additional parameters. If a projection does require additional parameters,
- up to three numbers specifying the orientation of
c(90, 0, m), where
mis the middle of the longitude range.
- logical flag that says whether to draw lines or fill areas.
FALSE, the lines bounding each region will be drawn (but only once, for interior lines). If
TRUE, each region will be filled using colors from the
- vector of colors.
FALSE, the first color is used for plotting all lines, and any other colors are ignored. Otherwise, the colors are matched one-one with the polygons that get selected by the
- logical flag that specifies whether plotting
should be done.
TRUEthe return value of
mapwill not be printed automatically .
- logical flag that specifies whether to add to the
FALSE, a new plot is begun, and a new coordinate system is set up.
TRUE, the return value will be a character vector of the names of the selected polygons. See the Value section below.
- two element numeric vector giving a range of longitudes, expressed in degreees, to which drawing should be restricted. Longitude is measured in degrees east of Greenwich, so that, in particular, locations in the USA have negative longi
- two element numeric vector giving a range of latitudes, expressed in degrees, to which drawing should be restricted. Latitude is measured in degrees north of the equator, so that, in particular, locations in the USA have positive
- If TRUE, lines that cross too far across the map (due to a strange projection) are omitted.
- number that specifies the resolution with which to draw the map. Resolution 0 is the full resolution of the database. Otherwise, just before polylines are plotted they are thinned: roughly speaking, successive points on the polyline that a
- character string that controls drawing of the map.
Aside from the default
type = "l", the value
type = "n"can be used to set up the coordinate system and projection for a map that will be added-to in later calls.
- background color
- margins, as in
- Extra arguments passed to
plot = TRUE, a plot is made where the polygons selected from
database, through the
ylimarguments, are outlined (
FALSE) or filled (
TRUE) with the colors in
The return value is a list with
namescomponents. This object can be used as a
databasefor successive calls to
mapand functions. If
yvectors are the coordinates of successive polylines, separated by
yvectors have coordinates of successive polygons, again separated by
NAs. Thus the return value can be handed directly to
polygon, as appropriate.
TRUE, only the names component is returned.
After a call to
mapfor which the
projectionargument was specified there will be a global variable
.Last.projectioncontaining information about the projection used. This will be consulted in subsequent calls to
projection = ''.
map(database = "world", regions = ".", exact = FALSE, boundary = TRUE, interior = TRUE, projection = "", parameters = NULL, orientation = NULL, fill = FALSE, color = 1, plot = TRUE, add = FALSE, namesonly = FALSE, xlim = NULL, ylim = NULL, wrap = FALSE, resolution = 1, type = "l", bg, mar, ...)
Richard A. Becker, and Allan R. Wilks,
"Maps in S",
AT&T Bell Laboratories Statistics Research Report [93.2], 1993.
Richard A. Becker, and Allan R. Wilks,
"Constructing a Geographical Database",
AT&T Bell Laboratories Statistics Research Report [95.2], 1995.
map() # low resolution map of the world map('usa') # national boundaries map('county', 'new jersey') # county map of New Jersey map('state', region = c('new york', 'new jersey', 'penn')) # map of three states map("state", ".*dakota") # map of the dakotas if(require(mapproj)) map('state', proj = 'bonne', param = 45) # Bonne equal-area projection of states # names of the San Juan islands in Washington state map('county', 'washington,san', names = TRUE, plot = FALSE) # national boundaries in one color, states in another # (figure 5 in the reference) map("state", interior = FALSE) map("state", boundary = FALSE, lty = 2, add = TRUE) # plot the ozone data on a base map # (figure 4 in the reference) data(ozone) map("state", xlim = range(ozone$x), ylim = range(ozone$y)) text(ozone$x, ozone$y, ozone$median) box()