On Mon, 8 Feb 2016, Josh O'Brien wrote:
Oops. The post's title should have read "rgeos::gBuffer( , byid=TRUE)
fails when...". (I inadvertently left out the `byid=TRUE` bit).
My apologies.
On Mon, Feb 8, 2016 at 9:59 AM, Josh O'Brien <joshmobr...@gmail.com> wrote:
Hello,
Not sure if this would be considered a bug, but it did recently bite
me (and might bite others using gBuffer(..., byid=TRUE)
programatically).
Thanks for a reproducible example - for rgeos 0.3-14 this gives a
segfault, in 0.3-16 an error as the data.frame has only one row, but three
Polygons objects are returned. As you note, the issue is triggered by
byid=TRUE but there is only one input object; only one buffer is created,
around the NE island.
I'll look into this - it'll need debugging in C, close to recent bug-fixes
(then concerned with pre-sp-MultiPoint object signalling - multiple
objects making up features).
And yes, this is a reasonable place to report, it should give users a
realistic view of how many corner cases actually exist and require
someone's attention.
Roger
library(sp)
library(rgdal)
library(rgeos)
## Example SpatialPolygonsDataFrame
x <- readOGR(system.file("etc/shapes", package="spdep"), "sids")[c(89,28),]
plot(x, col=c('dodgerblue', 'wheat'))
## Works fine on object with multiple @Polygons in @polygons, even
## if one of the @Polygons is multi-part
gBuffer(x, width=0.01, byid=TRUE)
## Works with a single single-part @Polygons object in @polygons
gBuffer(x[1,], width=0.01, byid=TRUE)
## Fails with a single _multi-part_ @Polygons object in @polygons
gBuffer(x[2,], width=0.01, byid=TRUE)
Thanks (and please let me know an rgeos-specific note like this would
be better posted elsewhere),
Josh O'Brien
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Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: roger.biv...@nhh.no
http://orcid.org/0000-0003-2392-6140
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