[GRASS-stats] unexpected error with readVECT6

[Roger Bivand]

On Mon, 10 Mar 2008, Jaros?aw Jasiewicz wrote:

> Hi
>
> I try to read vector line file with following 775 lines:
>
> v.info results:
>
> +----------------------------------------------------------------------------+
> |  Layer: 
> zb at trzy_mapy                                              |
> |  Mapset: 
> trzy_mapy                                                 |
> |  Location: 
> polska                                                    |
> |  Database: 
> /home/jarekj/grassdata                                    |
> | 
> Title:                                                                     |
> |  Map scale: 
> 1:1                                                       |
> |  Map format: 
> native                                                    |
> |  Name of creator: 
> jarekj                                                    |
> | 
> Organization:                                                              |
> |  Source date:     Mon Mar 10 16:03:03 
> 2008                                  |
> | ----------------------------------------------------------------------------|
> |    Type of Map:  vector (level: 
> 2)                                          |
> | 
> | 
> |    Number of points:       0               Number of areas: 
> 0          |
> |    Number of lines:        775             Number of islands: 
> 0          |
> |    Number of boundaries:   0               Number of faces: 
> 0          |
> |    Number of centroids:    0               Number of kernels: 
> 0          |
> | 
> | 
> |    Map is 3D: 
> 0                                                |
> |    Number of dblinks: 
> 1                                                |
> | 
> | 
> |          Projection: Transverse 
> Mercator                                    |
> |                N:    470423.4220965    S: 
> 429940.9545465                 |
> |                E:    561987.1623495    W: 
> 539556.8766255                 |
> | 
> | 
> |    Digitization threshold: 
> 0                                                |
> | 
> Comments:                                                                |
> | 
> | 
> +----------------------------------------------------------------------------+
>
>
>
>
>
> ........
> Geospatial Data Abstraction Library extensions to R successfully loaded
>>  v=readVECT6("zb", type="line")

The help page gives a relevant example. The problem is the possible 
existence of duplicates in the accompanying data frame. If there are known 
to be no duplicates, or it does not matter, use remove.duplicates=FALSE 
and then the final step assembling (lines or) polygons will not be carried 
out. There is a bug too, but I think that for your case, setting the 
argument will be a better resolution.

Please let me know if this helps,

Roger

> Exporting 775 points/lines...
> 100%
> 775 features written
> OGR data source with driver: ESRI Shapefile
> Source: "/home/jarekj/grassdata/polska/trzy_mapy/.tmp/jarekj-desktop", layer: 
> "zb"
> with  775  rows and  1  columns
> Error in Polygons(srl, ID = IDss[i]) : srl not a list of Polygon objects
>>  ls()
> character(0)
>
>
> why polygon????????
>
> Jarek
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>
>

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, 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