[R] distance matrix
Jose Andres
jaa53 at cornell.edu
Sat Jul 29 00:13:30 CEST 2006
Hi all,
I have a set of points (1...n) each of them defined on a 3D space
(i.e. for each point I do have x,y,z coordinates), and I would like
to generate a mean pairwise geometrical distance between them. Is
there anyway I can do this with R?
Conceptually is really simple. First I have to generate a distance
matrix (let's say "distmat") of pairwise distances (d= sqrt((x1-x2)^2
+ (y1-y2)^2+(z1-z2)^2) and then calculate the mean -- mean.matrix
(distmat) -- . However, I do not know how I can generate the distance
matrix using R. I'd really appreciate all your suggestions/comments.
So, I have
x y z
1 x1 y1 z1
2 x2 y2 z2
: : : :
n xn yn zn
and need
1 2 .. n
1 -
2 d12 -
:
n d1n d2n -
So I can calculate mean din
Thanks in advance!!!!!
Best,
/Jose
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