[R-sig-Geo] Singlepart to multipart

[Jonathan Greenberg]

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