A 'geoshapes' object containing one or more georeferenced shapes

Geoshapes objects contain one or more shapes (that is, polygons, points, or polylines) defined by their longitude and latitude in decimal degrees. These objects can be read or write to ERSI shape files.

geoshapes(x, name = "1", dbf = NULL)
read.geoshapes(shpFile, dbf = TRUE)
write.geoshapes(x, file, type = c("polygon", "point", "polyLine"),
    dbf = TRUE, arcgis = FALSE,...)

# S3 method for class 'geoshapes'
print(x, ...)
# S3 method for class 'geoshapes'
lines(x, which = 1, ...)
# S3 method for class 'geoshapes'
points(x, which = "all", ...)

Arguments

x: A data frame with columns 'x' and 'y' for longitudes and latitudes of the points in decimal degrees, or a list of such data frames for geoshapes(); a 'geoshapes' object for the other functions
name: The name to use for the shape in case a data frame is passed to geoshapes(). Ignored if a list is passed to the function
dbf: A data frame to record as 'dbf' attribute for geoshapes, or a flag indicating to read or write DBF data too, if the file exists
shpFile: The path to a .shp file (ESRI shape file) to import
file: The path to an ESRI file where to write data, without extension. Three files are created, with respective extensions .shp, .shx, and .dbf
type: The type of shape to write in the ESRI shape file
arcgis: If TRUE, the header of the DBF table is made compatible with ArcGIS, that is, dot (.) is replaced by underline (_)
which: The index of the shape to use, or its name
...: Further arguments passed to the functions (not used yet)

Details

geoshapes() converts a data frame or a list into a 'geoshapes' object. read.geoshapes() and write.geoshapes() read and write shapes from or to ESRI shape files on disk. The 'geoshapes' objects have methods to print them (very concisely), and to add them to graphs, as polygons lines(), or as separate points points().

Value

A 'geoshapes' object is returned from geoshapes() and read.geoshapes(). The other functions are used for their side-effect rather than for returning something useful.

Author

Philippe Grosjean <phgrosjean@sciviews.org>

Examples

data(mbord) # Morocco borders
mbord
#> A 'geoshapes' object containing one shape

# Plot of Morocco terrain and add the borders in red
data(morocco)
image(morocco)
lines(mbord, col = 2)


# Simulate the creation of a geoshapes object with two shapes
geoshapes(list(a = mbord[[1]], b = mbord[[1]]))
#> A 'geoshapes' object containing 2 shapes:
#> [1] "a" "b"