[R-sig-Geo] invalid class “SpatialPolygons” object: non-unique Polygons ID slot values

[Edzer Pebesma]

Looking at the code,

x = rbind(x1, x2, x3, makeUniqueIDs = TRUE)

ought to work, but I haven't tried.

You are right that neither ?rbind nor ?rbind.SpatialPolygons tells you
about this.


On 12/21/2013 12:16 PM, Agustin Lobo wrote:
> Had looked into the vignette. No, it does not really help. spRbind() is only
> mentioned in "2.1 Dissolving Polygons" and not in "3.1 Combining
> Positional Data".
> Including an example where the  "non-unique Polygons ID slot values" occurs in
> section 3.1. and the way to fix it using spRbind() would be very helpful. But
> having the same example in the help page also would be even better.
> I also find the Note
> "2. some rbind can accept objects with duplicated IDs,..."
> in the spRbind help page very confusing, as it is vague and the rbind
> help page does not mention spatial objects at all.
> 
> The error I mention is frequent when combining SpPolDF objects that
> come from  imported shapefiles
> and is probably rare in "only R" processing chains.
> 
> Thanks for caring about this.
> 
> Agus
> 
> On Fri, Dec 20, 2013 at 8:14 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>> On Fri, 20 Dec 2013, Agustin Lobo wrote:
>>
>>> Hi!
>>>
>>> I've got the "invalid class “SpatialPolygons” object: non-unique
>>> Polygons ID slot values"
>>> error at trying to use rbind() (or spRbind()) with two spatial
>>> polygons dataframes that
>>> come from readOGR() of shapefiles.
>>> Not having done this operation in a long while, It took me quite a
>>> long time to remember about the spChFIDs() solution
>>> (i.e.
>>> http://r-sig-geo.2731867.n2.nabble.com/rbind-of-SpPolDFs-td5070215.html)
>>> despite the fact that the help page of spRbind() mentions the
>>> spChFIDs-methods.
>>>
>>> Could an example in which spChFIDs() has to be run be added to the
>>> Examples of the spRbind help page?
>>> Actually I think that the case in which 2 spatial polygons dataframes
>>> have independently assigned IDs (and thus most often require the
>>> spChFIDs step) is more common than the case of the current example and
>>> many users just remain confused looking at the error "invalid class
>>> “SpatialPolygons” object: non-unique Polygons ID slot values".
>>
>>
>> Does:
>>
>> library(maptools)
>> vignette("combine_maptools")
>>
>> help?
>>
>> Roger
>>
>>>
>>> Also, could the rbind() help page contemplate the case of sp objects?
>>>
>>> Thanks
>>>
>>> Agus
>>>
>>> _______________________________________________
>>> R-sig-Geo mailing list
>>> R-sig-Geo at r-project.org
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>>
>>
>> --
>> 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 95 43
>> e-mail: Roger.Bivand at nhh.no
>>
>> _______________________________________________
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>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
> 
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-- 
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Heisenbergstraße 2, 48149 Münster, Germany. Phone: +49 251
83 33081 http://ifgi.uni-muenster.de GPG key ID 0xAC227795

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