pal2SpatialPolygons

0th

Percentile

Making SpatialPolygons objects from RArcInfo input

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

Keywords
spatial
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
Value

  • The functions return a SpatialPolygons object

Aliases
  • pal2SpatialPolygons
Examples
nc1 <- readShapePoly(system.file("shapes/sids.shp", package="maptools")[1], ID="FIPS")
plot(nc1)
text(coordinates(nc1), labels=sapply(slot(nc1, "polygons"),
 function(i) slot(i, "ID")), cex=0.6)
library(maps)
ncmap <- map("county", "north carolina", fill=TRUE, col="transparent",
 plot=FALSE)
IDs <- sapply(strsplit(ncmap$names, "[,:]"), function(x) x[2])
nc2 <- map2SpatialPolygons(ncmap, IDs)
plot(nc2)
text(coordinates(nc2), labels=sapply(slot(nc2, "polygons"),
 function(i) slot(i, "ID")), cex=0.6)
library(RArcInfo)
td <- tempdir()
tmpcover <- paste(td, "nc", sep="/")
if (!file.exists(tmpcover)) e00toavc(system.file("share/co37_d90.e00",
 package="maptools")[1], tmpcover)
arc <- get.arcdata(td, "nc")
pal <- get.paldata(td, "nc")
pat <- get.tabledata(paste(td, "info", sep="/"), "NC.PAT")
sapply(pal[[2]], function(x) length(x[[1]]))
IDs <- paste(pat$ST[-1], pat$CO[-1], sep="")
nc3 <- pal2SpatialPolygons(arc, pal, IDs=IDs)
plot(nc3)
text(coordinates(nc3), labels=sapply(slot(nc3, "polygons"),
 function(i) slot(i, "ID")), cex=0.6)
Documentation reproduced from package maptools, version 0.7-15, License: GPL (>= 2)

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