[R-sig-Geo] write.nb.gal doesn't include correct ID

[Roger Bivand]

On Mon, 12 Jul 2010, Roger Bivand wrote:

> On Thu, 8 Jul 2010, Chris Fowler wrote:
>
>> I am trying to write a rather large neighborhood list to a .gal file using 
>> the following code
>> write.nb.gal(Q1.nb, "Map 
>> Data/subWeights.gal",oldstyle=FALSE,shpfile="submap.shp",ind="ind")
>> 
>> where ind is an array of numbers representing FIPS codes at the census 
>> tract level (I also tried it using "STFID" which is the same data as a 
>> column in the shapefile submap.shp) while I don't get any errors, my .gal 
>> file uses the sequential id number from the shapefile (a meaningless 1 to n 
>> number assigned by ArcGIS in the creation of the shapefile). I have tried 
>> (in ArcGIS) converting the number assigned by ArcGIS to my FIPS codes using 
>> Field Calculator, but this doesn't seem to change anything. My concern is 
>> that the problem is perhaps the length of the FIPS codes which are 10 or 11 
>> digits each?
>> 
>> Is there something that I am missing that will allow me to use the more 
>> meaningful FIPS codes in the gal file?
>
>
> You must include more of your workflow. I suspect that the correct values are 
> not being set when the "nb" object is created (synax and argument names may 
> vary between functions). Please also explain which other software you are 
> using - ArcGIS is by no means available to everybody, I for example have no 
> access to this product.
>
> Work from a canned example, such as:
>
> library(spdep)
> example(nc.sids)
> nbs <- poly2nb(nc.sids, row.names=nc.sids$CNTY_ID)
> writeSpatialShape(nc.sids, "nc_sids.shp")
> write.nb.gal(nbs, "nc_sids.gal", oldstyle=FALSE, shpfile="nc_sids.shp",
>  ind="CNTY_ID")

By the way, these files read correctly in OpenGeoDa (here 0.9.8.14, 
Windows binary version running under Wine on Linux).

Roger

>
> and explain again what the problem is. By the way, Arc typically assigns a 
> FID which is 0-based, the 1-based indices are the default in functions making 
> "nb" objects when no alternative is given, so your analysis is more likely 
> guessing than actually what is happening. Note that you may also run into 
> problems with apparently numeric identifiers (like some FIPS) that begin with 
> "0", you'll have to feel your way there.
>
> Hope this helps,
>
> Roger
>
>> 
>> Thanks,
>> 
>> Chris Fowler
>> 
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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