[R-sig-Geo] Subset a SpLineDF

[Edzer Pebesma]

By assigning slots directly, you always take a serious risk that you
create objects that are considered invalid in a next step, as is the
case in your example.

My guess is that when you subset @data, you should also replace the
@lines slot with the corresponding subset of @lines (which is a list).

The more straightforward (and safe) way is to subset the whole object as
if it were a data.frame:

TRONCON_TOPO_DSAV_coor[! TRONCON_TOPO_DSAV_coord$doublon, ]

(note the absence of @)


On 22/02/17 11:49, Tristan Bourgeois wrote:
> Dear all,
> 
> I'm facing a problem I can't solve even if the solution should not be so
> hard to find.
> 
> I want to delete the duplicates in a spatial  line dataframe .Those
> duplicates have been created by shapesfiles merging on QGis (boundary
> rivers are duplicated by the merging of neighbouring departments layers)
> 
> So here's the code I wrote :
> 
> 
> TRONCON_TOPO_DSAV_coord <-readOGR(dsn = "Sorties/Tronçon
> BDTOPO/TRONCON_TOPO_DSAV/Avec coordonnées", layer =
> "TRONCON_TOPO_DSAV_coord")
> TRONCON_TOPO_DSAV_coord at data
> $doublon<-duplicated(TRONCON_TOPO_DSAV_coord at data$ID)### Create a fied for
> duplicate identification
> TRONCON_TOPO_DSAV_coord at data<-subset(TRONCON_TOPO_DSAV_coord at data
> ,TRONCON_TOPO_DSAV_coord at data$doublon=="FALSE")### Subset to delete the
> duplicate
> TRONCON_TOPO_DSAV_coord at data ### Checking results
> 
> writeOGR(TRONCON_TOPO_DSAV_coord,dsn =
> path,layer="TRONCON_TOPO_DSAV_coord_unique_test",driver ="ESRI Shapefile")
> 
> 
> When I want to export my OGR file,  I get this error message :"Error in
> writeOGR(TRONCON_TOPO_DSAV_coord, dsn = path, layer =
> "TRONCON_TOPO_DSAV_coord_unique_test",  :
>   number of objects mismatch
> 
> 
> It seems that I have not the same number of objects in the different
> shapefile slots.  How to update these objets after my subset ?
> 
> 
> Cheers !
> 
> "
> 

-- 
Edzer Pebesma
Institute for Geoinformatics  (ifgi),  University of Münster
Heisenbergstraße 2, 48149 Münster, Germany; +49 251 83 33081
Journal of Statistical Software:   http://www.jstatsoft.org/
Computers & Geosciences:   http://elsevier.com/locate/cageo/

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