[R-sig-Geo] problem with edit.nb

[Michał Kwieciński]

2010/8/26 Roger Bivand <Roger.Bivand at nhh.no>:
> On Thu, 26 Aug 2010, Michał Kwieciński wrote:
>
>> Hi all,
>>
>> I am just about to finish my thesis. The spatial model I want to use
>> there is an extension of some work I did back in April. I used R 2.9.2
>> then and in order to include 3 additional administrative areas for
>> Poland, I edited the shp files (the borders aren't perfectly aligned).
>> Then in R I created the nb class object and edited it with edit.nb
>> adding three new connections. Everything worked perfect, I had no
>> regions with no links and I generated weight matrices with no
>> problems.
>>
>> However, I'd been doing exactly the same thing entire night in R 2.11
>> and it did not work (I use the same code I did 4 months ago) and I
>> have no idea what is the reason for it. I've been looking for some
>> other way to do it, I tried nb2mat and editing the matrix, but I
>> surrendered having no idea where and what values I should use.
>>
>> Before editing nb object R claims that regions 377 and 378 have no
>> links. However in edit.nb the 378 and 379 are visible as having no
>> links (378 and 379 are cities added on top of bigger shapes, whereas
>> 377 was just split from a bigger shape into two smaller ones and only
>> the link between these two parts is missing). I connect the circles,
>> quit and in the new object there are some new links - the overall
>> number has increased - but 377 and 378 are still listed as having no
>> links. Editing nb again shows the links, so they have been saved for
>> sure.
>>
>> I am not an advanced R user and most of my code was based on my
>> professor's book. However, I think I have spent enough time with
>> spatial models and those matrices in order to call this problem really
>> weird. Especially since it worked perfectly last time...
>>
>> I can attach shp files and my code if it will be of any help in order
>> to properly investigate this problem. I would really appreciate some
>> help, I need to finish the project over the weekend.
>
> Maybe you are using the wrong indices, as FIDs are 0-base but nb objects are
> 1-base. So you may be editing the wrong ones. If this doesn't resolve the
> problem, zip the shapefile and post a link to it, don't attach the
> shapefile, as it would be sent to 1700 people.


I must admit I did not understand your hint (I do not know what "base"
is, assuming FID is Field ID - header in shp file). How is it possible
I edited some other layer of information by function edit.nb? Could
you please clarify what should I do to check it?

Thank you for prompt reply,
Michal