[R-sig-Geo] Singlepart to multipart

[Robert J. Hijmans]

Jonathan,
You can go back and forth with (raster/sp) functions aggregate and disaggregate
Robert

On Tue, Apr 1, 2014 at 7:50 AM, Jonathan Greenberg <jgrn at illinois.edu> wrote:
> This is a counter-question to the previous one: how would I go about
> taking a multipart SpatialPolygon* and "flattening" it so each
> individual polygon is its own component, "repeating" the data frame
> (if a SpatialPolygonsDataFrame) for the new polygons, effectively
> "undoing" the previous suggestion?
>
> --j
>
> On Tue, Oct 29, 2013 at 2:32 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
>> On Tue, 29 Oct 2013, Jonathan Greenberg wrote:
>>
>>> R-sig-geo'ers:
>>>
>>> If I have a SpatialPolygonsDataFrame with a field "MYID", how do I go
>>> about
>>> coercing that object to a multipart polygon, where I am "merging" on the
>>> MYID field?
>>
>>
>> maptools::unionSpatialPolygons() which calls rgeos::gUnaryUnion, so go to
>> rgeos::gUnaryUnion first unless you have challenged geometries - if hole
>> problems use maptools::checkPolygonsHoles first.
>>
>> Hope this helps,
>>
>> Roger
>>
>>>
>>> --j
>>>
>>>
>>
>> --
>> 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.Bivand at nhh.no
>>
>
>
>
> --
> Jonathan A. Greenberg, PhD
> Assistant Professor
> Global Environmental Analysis and Remote Sensing (GEARS) Laboratory
> Department of Geography and Geographic Information Science
> University of Illinois at Urbana-Champaign
> 259 Computing Applications Building, MC-150
> 605 East Springfield Avenue
> Champaign, IL  61820-6371
> Phone: 217-300-1924
> http://www.geog.illinois.edu/~jgrn/
> AIM: jgrn307, MSN: jgrn307 at hotmail.com, Gchat: jgrn307, Skype: jgrn3007
>
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