spatially clustered factors?

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.

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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