replace dist with mahalanobis distance in the following example.
a <- cbind(runif(10), sample(1:3, 10, replace=T))
a.L <- split(a,a[,2])
dist.L <- lapply(a.L, dist)
Nikhil Kaza
Asst. Professor,
City and Regional Planning
University of North Carolina
nikhil.l...@gmail.com
On Jul 19, 2010, at 9:24 AM, Michael Ralph M. Abrigo wrote:
Hi! I am trying to implement non-bipartite matching. I have around
500 sites
which can be clustered by 10 regions. I am able to calculate pairwise
Mahalanobis distances between sites (thanks to another post in the
forum).
However, I want to constrain my match to sites within the same
region. Thus
I want to replace elements of the distance matrix with a high value,
say
999999, for sites not of the same region so that the pair will not be
matched.
In the original data file I have information on which sites belong
to what
region. However, when I compute for pairwise Mahalanobis distances,
I only
use a subset of the file, which, naturally, does not include the
georeference of the sites. How should I do this? Any hint will be most
appreciated.
Btw, I am relatively new in using R. I may export the matrix to
another
program and replace the elements there, but that is a very very
dirty and
rough trick that I would rather not do given better options.
Many thanks in advance.
Cheers,
Michael
--
"I am most anxious for liberties for our country... but I place as a
prior
condition the education of the people so that our country may have an
individuality of its own and make itself worthy of liberties... " Jose
Rizal,1896
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