Spatial weight matrix of distance in the Mata

[Rafaella Stradiotto]

Hello,
I would like to know how to generate spatial weight matrix of distance in the Mata. Could I do that? Which command to use?
I'm trying to generate the matrix in STATA, with the following command:

spatwmat, name(W) xcoord(longitude) ycoord(latitude) band(0 5) standardize
However, being a very large matrix (5564x5564), the STATA is locking and does not generate the matrix.
Anyone have suggestions to help me?
Thank you.

[Matthew J. Baker]

Rafaella --

Something like the following should do the trick (I hope I haven't messed up the distance calculation!) On my computer, I can make a 6000 by 6000 distance matrix, but I then have a little trouble doing anything with it. Anyways:

clear all
mata
real matrix distances(real colvector x, real colvector y) {
    D=J(rows(x),rows(x),.)
    for (i=1;i<=rows(x);i++) D[i,]=sqrt((x:-x[i]):^2:+(y:-y[i]):^2)'
    return(D)
}

/* Test */
/* Column vectors of coordinates required */

x=runiform(6000,1)
y=runiform(6000,1)

D=distances(x,y)
end

Hope that helps!

Matt

[Rafaella Stradiotto]

Hi Matt,

I will test the programming that you suggested.
Thank you so much for the return.
Rafa.