[R-sig-Geo] Never post using an existing thread (this is also in the wrong thread)

[Roger Bivand]

On Fri, 14 Mar 2014, Milan Sharma wrote:

Never post using an existing thread on a different topic (here: How to 
shrink a spatial shape? Or calculate distances btw points and a polygon?). 
This messes up the archives, and cannot be understood by those reading 
digested lists of postings, as well as confusing those active in the 
existing discussion thread.

If you want to post to the list, start a new, empty email, and remember 
not to post HTML, only plain text.

>
>
> Hi all,
> I know there are several postings on this problem, but that did not help to solve my problem
> sarlm<-lagsarlm(Agr_2001~Gras_2001+For_2001,data=data1,listw=qw)
> Error in solve.default(inf, tol = tol.solve) :
> system is computationally singular: reciprocal condition number = 4.22828e-37
> How do I solve this issue?
> Milan
>
>
>
> On Friday, March 14, 2014 1:55 PM, Barry Rowlingson <b.rowlingson at lancaster.ac.uk> wrote:
>
> On Fri, Mar 14, 2014 at 12:11 PM, Roman Lu??trik <roman.lustrik at gmail.com>wrote:
>
>> Can you plot a circle (or some other shape) around each store and find the
>> difference between your polygon and the 'store buffer'? Alternatively, you
>> can shrink your entire polygon. See `rgeos` package, say `gBuffer`
>> function.
>>
>
> Yes, you use gBuffer with a negative distance.:
>
>> require(rgeos)
>> p2 = readWKT("POLYGON((2 2,-2 2,-2 -2,2 -2,2 2),(1 1,-1 1,-1 -1,1 -1,1
> 1))")
>> plot(p2)
>> plot(gBuffer(p2,width=-0.2),add=TRUE,col="red")
>
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>
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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
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