pal2SpatialPolygons: Making SpatialPolygons objects from RArcInfo input

In maptools: Tools for Handling Spatial Objects

Making SpatialPolygons objects from RArcInfo input

Description

This function is used in making SpatialPolygons objects from RArcInfo input.

Usage

pal2SpatialPolygons(arc, pal, IDs, dropPoly1=TRUE,
 proj4string=CRS(as.character(NA)))

Arguments

IDs	Unique character ID values for each output Polygons object; the input IDs can be an integer or character vector with duplicates, where the duplicates will be combined as a single output Polygons object
proj4string	Object of class "CRS"; holding a valid proj4 string
arc	Object returned by get.arcdata
pal	Object returned by get.paldata
dropPoly1	Should the first polygon in the AVC or e00 data be dropped; the first polygon is typically the compound boundary of the whole dataset, and can be detected by looking at the relative lengths of the list components in the second component of pal, which are the numbers of arcs making up the boundary of each polygon

Value

The functions return a SpatialPolygons object

Author(s)

Roger Bivand

Examples

nc1 <- readShapePoly(system.file("shapes/sids.shp", package="maptools")[1], ID="FIPS")
plot(nc1)
text(coordinates(nc1), labels=row.names(nc1), cex=0.6)
if(require(maps)){
ncmap <- map("county", "north carolina", fill=TRUE, col="transparent",
 plot=FALSE)
IDs <- sapply(strsplit(ncmap$names, "[,:]"), function(x) x[2])
nc2 <- map2SpatialPolygons(ncmap, IDs)
plot(nc2)
text(coordinates(nc2), labels=row.names(nc2), cex=0.6)
}
#if(require(RArcInfo)) {
#td <- tempdir()
#tmpcover <- paste(td, "nc", sep="/")
#if (!file.exists(tmpcover)) e00toavc(system.file("share/co37_d90.e00",
# package="maptools")[1], tmpcover)
#arc <- get.arcdata(td, "nc")
#pal <- get.paldata(td, "nc")
#pat <- get.tabledata(paste(td, "info", sep="/"), "NC.PAT")
#sapply(pal[[2]], function(x) length(x[[1]]))
#IDs <- paste(pat$ST[-1], pat$CO[-1], sep="")
#nc3 <- pal2SpatialPolygons(arc, pal, IDs=IDs)
#plot(nc3)
#text(coordinates(nc3), labels=row.names(nc3), cex=0.6)
#}

maptools documentation built on July 26, 2023, 5:38 p.m.