Weight Matrices from Distance Matrix

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Weight Matrices from Distance Matrix

Postby CharlieEVIEWS » Tue Feb 24, 2015 3:47 am

Dear All,

Please see some code to create 5 commonly used spatial weighting matrices based on distances (k-nearest, radial distances, power distances, exponential distances and double-power distances). The idea is to use this in conjuction with a well specified distance matrix (in the code below, called distance_haversine):

Code: Select all

!rwd_max = 0.5

matrix(@rows(distance_haversine),@rows(distance_haversine)) knearest_matrix = 0 ' k-Nearest Neighbor Weights.
vector(@rows(distance_haversine)) rankvect
for !p = 1 to @rows(distance_haversine)
   rankvect(!p) = !p
for !a = 1 to (@rows(distance_haversine))
   vector(@rows(distance_haversine)) sorted_ranks_{!a}
   sorted_ranks_{!a}=@capplyranks(rankvect,@ranks(@rowextract(distance_haversine,!a) ,"a,","r"))
   for !k = 2 to !k_nearest+1
   d sorted_ranks_{!a}

matrix(@rows(distance_haversine),@rows(distance_haversine)) rwd_matrix = 0 'Radial Distance Weights.
matrix(@rows(distance_haversine),@rows(distance_haversine)) dpdw_matrix = 0 ' Double-Power Distance Weights.
matrix(@rows(distance_haversine),@rows(distance_haversine)) pwd_matrix = 0 'Power Distance Weights.
matrix(@rows(distance_haversine),@rows(distance_haversine)) ewd_matrix = 0 'Exponential Distance Weights
for !a = 1 to @rows(distance_haversine)
    for !b = !a to @rows(distance_haversine)
      if !a<>!b then
         if distance_haversine(!a,!b)<!dpd_max then
         if distance_haversine(!a,!b)<!rwd_max then
            rwd_matrix(!a,!b) = 1
            rwd_matrix(!b,!a) = 1
         if distance_haversine(!a,!b)<>0 then   
            pwd_matrix(!a,!b) = distance_haversine(!a,!b)^(-{!pdw_weight})   
            pwd_matrix(!b,!a) = pwd_matrix(!a,!b)
            ewd_matrix(!a,!b) = @exp(-{!epw_weight}*distance_haversine(!a,!b))
            ewd_matrix(!b,!a) = ewd_matrix(!a,!b)

If there are any questions or requests, please don't hesitate to ask.

Last edited by CharlieEVIEWS on Tue Feb 24, 2015 7:03 am, edited 1 time in total.

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Re: Weight Matrices from Distance Matrix

Postby trubador » Tue Feb 24, 2015 6:46 am

Very intuitive and straightforward. Thanks for sharing.

Posts: 31
Joined: Wed Aug 03, 2011 4:35 am

Re: Weight Matrices from Distance Matrix

Postby Amber » Mon Aug 21, 2017 7:21 am

Dear @CharlieEVIEWS,

Thank you for sharing, this is very useful. Are you happen to know how to implement the spatial autoregressive or spatial error model in Eviews?



Posts: 202
Joined: Tue Jul 17, 2012 9:47 am

Re: Weight Matrices from Distance Matrix

Postby CharlieEVIEWS » Tue Aug 22, 2017 8:00 am

A while back I was building add-ins to estimate these models in EViews using James LeSages matlab toolbox as a guide, but I remember hitting a barrier somewhere and forget exactly what it was. Possibly to do with a matrix decomposition function that EViews didnt provide off the shelf at the time: one that I couldn't quickly figure out how to program efficiently and moved on to something else...

I'll revisit this when I have a bit more time though - perhaps in the next few weeks - thanks for reminding me!


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