Hi everyone,

The Spatial Dependence (spdep) library, has a function called 'dnearneigh', which identifies neighbours of region points by Euclidean distance between lower (greater than) and upper (less than or equal to) bounds.  The function returns a list of integer vectors giving the region id numbers for neighbours satisfying the distance criteria.

I have used this to identify the euclidean distance of all points falling within 0-2000m of each of my surveys locations.  Once distances are converted to inverse euclidean distances, the list looks something like this:

[[1]]
[1] 15.617376  0.535176  0.569497

[[2]]
[1] 15.6173762  0.5415378  0.5773159

[[3]]
[1] NA
 
etc.

For each of these points I also have presence/absence data for a particular owl species (all the location, PA, etc. is kept in a single data frame).  Is there a way of creating a similar list to the one above, identifying the Presence or Absence of an owl at each of the points that fall with in 0-2000m of the interested site??

I am attempting to determine the following equation for each site, at a number of spatial lags, i.e. 0-2000, 0-4000, etc
   
        Autocovariatei =  Sum wij  yj / Sum wij      

 

        Variables:         Autocovariate for stop i           

                                yj = Presence (1) or Absence (0) at stop j

                                wij = the inverse Euclidean distance between stops i and j 

Any help would be greatly appreciated.

Mark
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