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. cygwin_clean_temp
can be called to try to clean the GRASS mapset-specific temporary directory under cygwin.
readVECT6(vname, type=NULL, plugin=NULL, remove.duplicates = TRUE, ignore.stderr = FALSE, with_prj=TRUE, with_c=FALSE, mapset=NULL, pointDropZ=FALSE) writeVECT6(SDF, vname, v.in.ogr_flags=NULL, 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, ignore.stderr = FALSE) putSites6(df, vname, ignore.stderr = FALSE) getSites6sp(vname, ignore.stderr = FALSE, with_prj=TRUE) getSites6(vname, ignore.stderr = FALSE, with_prj=TRUE) cygwin_clean_temp(verbose=TRUE, 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 |
plugin |
default NULL for auto-detection, may be set to FALSE to avoid or TRUE if the plugin is known to be available; if the plugin is used, no further arguments other than mapset are respected |
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 |
with_prj |
default TRUE, write ESRI-style PRJ file for transfered data |
with_c |
if TRUE, export features with category (labeled) only; by default all features are exported |
mapset |
if plugin is TRUE, the mapset of the file to be imported may be changed from the current mapset by passing a character string |
pointDropZ |
default FALSE, if TRUE, discard third coordinates for point geometries; third coordinates are alway discarded for line and polygon geometries |
SDF |
A Spatial*DataFrame to be moved to GRASS6 as a vector object, for SpatialPointsDataFrame, SpatialLinesDataFrame, and SpatialPolygonsDataFrame objects |
v.in.ogr_flags |
Character vector 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) |
verbose |
TRUE, can be set to false |
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.
Please note that the OGR drivers used may not handle missing data gracefully. From rgdal release 0.5-27, missing values are taken as unset OGR field values. If the OGR driver encodes them in this way, NAs will be moved across the interface correctly from R to GRASS, and from GRASS to R using the OGR GRASS vector plugin. Work is continuing to correct v.out.ogr so that it emits unset fields, which affects users with no OGR GRASS plugin for the present. Thanks to Dylan Beaudette for helping with missing data handling.
Please also note that, on Windows and Cygwin systems, the temporary shapefiles are not removed by the interface functions, nor can GRASS remove them on termination - they must for the time being be removed manually. Windows believes that the GDAL/OGR library is still using them.
Roger S. Bivand, e-mail: Roger.Bivand@nhh.no.
if (nchar(Sys.getenv("GISRC")) > 0) { execGRASS("v.info", parameters=list(map="bugsites")) print(vInfo("bugsites", ignore.stderr=TRUE)) bugs <- readVECT6("bugsites", ignore.stderr=TRUE, plugin=NULL) print(summary(bugs)) bugs1 <- readVECT6("bugsites", ignore.stderr=TRUE, plugin=FALSE) print(summary(bugs1)) writeVECT6(bugs, "newbugs", v.in.ogr_flags=c("o", "overwrite"), ignore.stderr=TRUE) execGRASS("v.info", parameters=list(map="newbugs")) nbugs <- readVECT6("newbugs", ignore.stderr=TRUE) print(summary(nbugs)) print(vInfo("roads", ignore.stderr=TRUE)) roads <- readVECT6("roads", ignore.stderr=TRUE) print(summary(roads)) }