I dont know about correlogram, but you can create a variogram map using gstat package. A from there you can see spatial variation and direction of this variation...

Matevz U. Pavlic

On 13. jul. 2011, at 14:16, "Sadz A" <sadz_a1000@yahoo.co.uk> wrote:

> Dear list,
> 
> I am trying to explore spatial patterns in some density data that I have (attached txt- RDdensityChange). I have successfully carried out Moran's I correlogram on the data using the library (pgirmess). I now wish to carry out an anisotropic correlogram, I have looked at the ncf and ape packages but I am failing to get the out put I want: 
> 
> I would like to find the direction in which the change is occurring, how significant it is etc.  
> 
> To do this I believe I need to calculate the distance between points (municipXY.txt attached is the latitude longitude location of my data points) when they are projected onto a perpendicular line (of angle 0 ie. north line). use the distances calculated to to run a new morans I. And then repeat for a new angle (eg 45 degrees (North east), 90 degrees (east) etc). 
> 
> Unfortunately I don't know how to do this, I am very new to spatial analysis and R. 
> I would greatly appreciate any help on this matter. 
> 
> Thank you for your time, 
> S.
> <RDdensityChange.txt>
> <municipXY.txt>
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