On Sun, 28 Oct 2012, Barry Rowlingson wrote:
On Sun, Oct 28, 2012 at 12:22 PM, O'Hanlon, Simon J <simon.ohan...@imperial.ac.uk> wrote:Dear list,#Reproducible exampleI think maptools isn't coping with certain types of tess object. I can reproduce this in three lines without needing a download :)
I'm seeing: Warning message: In as.polygonal(x) : Can't convert mask to polygon: gpclib is disabled/unavailable called in maptools:::owin2Polygons: x <- as.polygonal(x)where x is an element of the list y made from the tesselation in maptools:::as.SpatialPolygons.tess by
y <- tiles(x)Since as.polygonal(x) fails, x$bdry is NULL, and pieces is an empty list. I've patched sp:::Polygons() to trap the empty list on R-Forge, so that the user will see (using the current status of rspatial/sp on R-Forge):
vp <- as( v , "SpatialPolygons" )
Error: length(srl) > 0 is not TRUE
In addition: Warning message:
In as.polygonal(x) :
Can't convert mask to polygon: gpclib is disabled/unavailable
The resolution for now is:
spatstat.options("gpclib"=TRUE)
letting as.polygonal() do its stuff for a W$type "mask" tesselation. Not
great, but it works; conversion to rgeos from gpclib might also work
using the wrappers for gpclib objects included in rgeos.
Roger
1, start R, use some packages: $ R --vanilla R version 2.15.1 (2012-06-22) -- "Roasted Marshmallows" Copyright (C) 2012 The R Foundation for Statistical Computing ISBN 3-900051-07-0 Platform: i486-pc-linux-gnu (32-bit) R is free software and comes with ABSOLUTELY NO WARRANTY. You are welcome to redistribute it under certain conditions. Type 'license()' or 'licence()' for distribution details. Natural language support but running in an English locale R is a collaborative project with many contributors. Type 'contributors()' for more information and 'citation()' on how to cite R or R packages in publications. Type 'demo()' for some demos, 'help()' for on-line help, or 'help.start()' for an HTML browser interface to help. Type 'q()' to quit R.library(spatstat)Loading required package: mgcv This is mgcv 1.7-21. For overview type 'help("mgcv-package")'. Loading required package: deldir deldir 0.0-20 spatstat 1.28-2 Type ‘help(spatstat)’ for an overview of spatstat ‘latest.news()’ for news on latest version ‘licence.polygons()’ for licence information on polygon calculations 2. Run this to create some objects:example(tess)tess> A <- tess(xgrid=0:4,ygrid=0:4) tess> A Tessellation Tiles are equal rectangles, of dimension 1 x 1 units 4 by 4 grid of tiles window: rectangle = [0, 4] x [0, 4] units tess> B <- A[c(1, 2, 5, 7, 9)] tess> B Tessellation Tessellation is determined by a factor-valued image with 5 levels window: binary image mask 384 x 192 pixel array (ny, nx) enclosing rectangle: [0, 3] x [1, 4] units tess> v <- as.im(function(x,y){factor(round(5 * (x^2 + y^2)))}, W=owin()) tess> levels(v) <- letters[seq(length(levels(v)))] tess> E <- tess(image=v) tess> E Tessellation Tessellation is determined by a factor-valued image with 11 levels window: binary image mask 128 x 128 pixel array (ny, nx) enclosing rectangle: [0, 1] x [0, 1] units 3. Try conversion:as(E,"SpatialPolygons")Error in as(E, "SpatialPolygons") : no method or default for coercing "tess" to "SpatialPolygons" 4. Try conversion with maptools:library(maptools)Loading required package: foreign Loading required package: sp Loading required package: lattice Checking rgeos availability: TRUEas(E,"SpatialPolygons")*** caught segfault *** address (nil), cause 'memory not mapped' I've not looked at the maptools code, but the tess object can be one of three types according to ?tess, and I bet the conversion code doesn't check what its dealing with... Barry _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
-- Roger Bivand Department of Economics, NHH Norwegian School of Economics, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 e-mail: roger.biv...@nhh.no
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