Hi,

This function is available in spgrass::vect2neigh

"vect2neigh return area neighbours with shared boundary length"

It requires installing GRASS


2012/1/23 Gaston Pezzuchi <gpezzuchi@yahoo.com.ar>

> Hi there:
>
> I am trying to find the actual formula to calculate the length of the
> common border between adjacent  polygons. So far I've been using:
>
> - Let r1 and r2 be the perimeters of Polygons 1 and 2.
> - Make R = r1 + r2
> - Make r = perimeter of the union between r1 and r2
> - Length of common border = (R - r)/2
>
>
>   This seems to work well if the common border is a single line segment,
> yet
> if the common border is comprised by more than one segment (two or more
> disjoint line segments), it will not work.
>
>    Any help would be greatly appreciated.
>
> Regards
>
> Gaston
>
> Lic. Gastón Pezzuchi
> Magister UNIGIS en Sistemas de Información Geográfica
>
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>
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