readVECT6 {spgrass6} | R Documentation |
readVECT6
moves one GRASS 6.0 vector object file with attribute data through a temporary shapefile to a Spatial*DataFrame object of type determined by the GRASS 6.0 vector object; writeVECT6
moves a Spatial*DataFrame object through a temporary shapefile to a GRASS vector object file. vect2neigh
returns neighbour pairs with shared boundary length as described by Markus Neteler, in https://stat.ethz.ch/pipermail/r-sig-geo/2005-October/000616.html.
readVECT6(vname, type=NULL, remove.duplicates = TRUE, ignore.stderr = FALSE) writeVECT6(SDF, vname, factor2char = TRUE, v.in.ogr_flags="", ignore.stderr = FALSE) vInfo(vname, ignore.stderr = FALSE) vColumns(vname, ignore.stderr = TRUE) vDataCount(vname, ignore.stderr = TRUE) vect2neigh(vname, ID=NULL, ignore.stderr = FALSE) putSites6sp(SPDF, vname, factor2char = TRUE, ignore.stderr = FALSE) putSites6(df, vname, ignore.stderr = FALSE) getSites6sp(vname, ignore.stderr = FALSE) getSites6(vname, ignore.stderr = FALSE)
vname |
A GRASS 6.0 vector file name |
type |
override type detection when multiple types are non-zero, passed to v.out.ogr |
remove.duplicates |
In line and area vector objects, multiple geometrical features may be associated with a single cat number, leading to duplication of data rows; this argument attempts to combine the geometrical features so that they match a single data row |
ignore.stderr |
default FALSE, can be set to TRUE to silence system output to standard error; does not apply on Windows platforms |
SDF |
A Spatial*DataFrame to be moved to GRASS6 as a vector object, for SpatialPointsDataFrame, SpatialLinesDataFrame, and SpatialPolygonsDataFrame objects |
factor2char |
logical, default TRUE, convert factor columns to character |
v.in.ogr_flags |
String containing additional optional flags and/or options for v.in.ogr, particularly -o and –overwrite |
ID |
A valid DB column name for unique identifiers (optional) |
SPDF |
A SpatialPointsDataFrame to be moved to GRASS6 as vector points |
df |
A data frame with at least columns named x, y and cat (no z support yet) |
readVECT6
imports a GRASS6 vector object into a Spatial*DataFrame object with the type determined by the type of the GRASS6 vector object; getSites6
returns a data frame. vect2neigh
returns a data frame object with left and right neighbours and boundary lengths, also given class GRASSneigh and spatial.neighbour (as used in spdep). The incantation to retrieve the neighbours list is sn2listw(vect2neigh())$neighbours
, and to retrieve the boundary lengths: sn2listw(vect2neigh())$weights
. The GRASSneigh object has two other useful attributes: external is a vector giving the length of shared boundary between each polygon and the external area, and total giving each polygon's total boundary length.
Roger S. Bivand, e-mail: Roger.Bivand@nhh.no.
if (nchar(Sys.getenv("GISRC")) > 0) { system("v.info bugsites") vInfo("bugsites", ignore.stderr=TRUE) bugs <- readVECT6("bugsites", ignore.stderr=TRUE) summary(bugs) writeVECT6(bugs, "newbugs", v.in.ogr_flags="-o --overwrite", ignore.stderr=TRUE) system("v.info newbugs") vInfo("streams", ignore.stderr=TRUE) streams <- readVECT6("streams", type="line,boundary", remove.duplicates=FALSE, ignore.stderr=TRUE) summary(streams) }