[R-sig-Geo] spatially clustered factors?

[Roger Bivand]

On Mon, 1 Jul 2013, Chris Mcowen wrote:

> Dear list, first let me apologise, i am an ecologist and this is my first
> foray into spatial statistics.
>
>
>
> I have, for a number of regions, the factor that best explains variation in
> the yield (fisheries catch) obtained within that region, the factor has 4
> levels - ChlA, SST, Effort or none.

See joincount.test for single comparisons, or joincount.multi for multiple 
comparisons by join "colours" in spdep. You'll also need neighbour lists, 
explained in:

vignette("nb")

in the most recent version of that package.

Hope this helps,

Roger

>
>
>
> What i am essentially wanting to know is,  is there a spatial pattern to the
> data? (clumped, over-dispersed or random)
>
>
>
> For example if region 1 is classed as Effort, is it more or less likely that
> the adjoining region (region 2) will be of the same factor, or does it makes
> no difference.
>
>
>
> I have seen lots of packages that allow this to be done for numerical data
> but have not found one for factors.
>
>
>
> Please see below for an example of the data. Where latitude is the centroid
> of the region and factor is the source of variation.
>
>
>
> clusters <- structure(list(Latitude = c(4.8261, 26.127123, 3.409063,
> -31.964573,
> 11.524328, 10.857926, 30.95066, 6.322733, 40.963009, -4.370738,
> 53.77057, -46.270909, 51.431808, 50.091992, -12.606217, 16.26404,
> -27.513126, -40.976427, -40.491914, -35.169487, -16.739053, -22.651113,
> 30.445027, -27.701939, -17.154608, -10.147356, -29.117245, 57.472215,
> 45.538569, 65.31731, 75.308501, 54.063299, 45.194528, 41.079154,
> -35.169487, 51.431808, 24.647845, 68.201714, 41.262656, 24.976371,
> 33.251908, 16.347456, 30.95066, -1.408364, 37.054319, 23.843305,
> 57.400753, 8.712258), Factor = structure(c(1L, 1L, 1L, 1L, 1L,
> 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
> 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L,
> 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L), .Label = c("ChlA",
> "Effort", "SST", "Unidentified"), class = "factor")), .Names = c("Latitude",
>
> "Factor"), class = "data.frame", row.names = c(NA, -48L))
>
>
>
>
>
> Thanks,
>
>
>
> Chris
>
>
>
>
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>
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-- 
Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
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