help on moran's I index of point pattern, not areal pattern

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help on moran's I index of point pattern, not areal pattern

zhijie zhang
hi,friends,
 we all know that moran's I index and Geary'C index can be used to test
spatial autocorrelation in both the area data and point data, but i only can
find something on how to calculate on the data of area, and can't find the
methods to perform it on the point data, could anybody give me some
information, thanks in advance!

--
Kind Regards,
Zhi Jie,Zhang ,PHD
Department of Epidemiology, School of Public Health, Fudan University
Tel:86-21-54237149

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Re: help on moran's I index of point pattern, not areal pattern

Roger Bivand
On Wed, 15 Mar 2006, zhijie zhang wrote:

> hi,friends,
>  we all know that moran's I index and Geary'C index can be used to test
> spatial autocorrelation in both the area data and point data, but i only can
> find something on how to calculate on the data of area, and can't find the
> methods to perform it on the point data, could anybody give me some
> information, thanks in advance!

There is no difference between area and point data given a
Voronoi/Dirichlet tesselation. To use any such index, you are obliged to
define neighours anyway, and whether you use a distance criterion,
k-nearest neighbours, triangulation, or a graph criterion such as a
minimum spanning tree, the duality remains.

Functions for defining neighbours are found in ade4 and spdep, and suit
points at least adequately. If you want a distance-based correlogram,
define increasing distance bands (or see the off-CRAN ncf package).

The functions are (among others) mstree() in ade4 taking a distance matrix
as its argument, and dnearneigh(), knearneigh(), tri2nb(), gabrielneigh(),
relativeneigh(), and soi.graph()  taking a matrix of 2D coordinates as
their argument in spdep (if your points are a regular grid, there is also
cell2nb()). At least you have a choice here.

>
> --
> Kind Regards,
> Zhi Jie,Zhang ,PHD
> Department of Epidemiology, School of Public Health, Fudan University
> Tel:86-21-54237149
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> [hidden email] mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>

--
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: [hidden email]

______________________________________________
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Roger Bivand
Department of Economics
NHH Norwegian School of Economics
Helleveien 30
N-5045 Bergen, Norway