[GRASS-stats] Problem with v.distance in spgrass6 package in R

[Roger Bivand]

On Fri, 28 Oct 2011, toke wrote:

>
> I think that I might have found a bug in spgrass6 or I might be doing
> something wrong. When I call v.distance within R it seems to calculate but
> it do not update the column of interest.
>
> Im using the the following software:
>
> platform    x86_64-pc-linux-gnu 10.10
> language   R
> version.string R version 2.13.2 (2011-09-30)
>
> Here are my script
>
> R
>
> #calling library
> library(spgrass6)
> # checking GRASS setup
> gmeta6()
>
> output:
> gisdbase    /home/toke/Desktop/PHD/databehandling/artikel_3/gis/grassdb
> location    mapset
> mapset      aalborg
> rows        1200
> columns     1100
> north       6328400
> south       6316400
> west        551800
> east        562800
> nsres       10
> ewres       10
> projection  +proj=utm +no_defs +zone=32 +a=6378137 +rf=298.257222101
> +to_meter=1
>
> # reading spatial files from GRASS database
> recrea_h <-readVECT6("recrea_h")
> area_b1 <-readVECT6("area_b1")
>
> execGRASS("v.distance", flags=c("overwrite"), from="recrea_h", to="area_b1",
> from_type="centroid", to_type="area", dmax=as.integer(1),
> + upload="to_attr", column="area_b1", to_column="value")
> 100%
> 100%
> 84 categories - no nearest feature found
> 235 categories read from the map
> 235 categories exist in the table
> 235 categories read from the map exist in the table
> 235 records updated
> v.distance complete.
>
> The column is not updated even though it seems that it is actually are
> calculating.
>
> The same calculation in GRASS works.

Please show your exact GRASS command line - otherwise we can only conclude 
that you are asking for different things. You are asking for a maximum 
distance of integer 1 metres here, so you should look carefully at the 84 
categories - no nearest feature found message - did that also appear in 
the output from running the command directly in GRASS?

Roger

>
> Cheers Toke
>
>
> --
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-- 
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