[R] mahalanobis distance
Rolf Turner
r.turner at auckland.ac.nz
Mon Jul 20 22:44:06 CEST 2009
On 21/07/2009, at 7:57 AM, Michael Knudsen wrote:
> On Mon, Jul 20, 2009 at 9:37 PM, ekinakoglu<ekin at ims.metu.edu.tr>
> wrote:
>
>> Could you please help me with a pseudo matrix of 4x4
>> that is gonna work with mahalanobis?
Please speak English. ``gonna'' is not appropriate
for written communication.
> Hmmm ... I have been trying some different matrices myself now, but I
> keep getting the same error. Even if det(S) is very far from zero.
> Maybe I just don't get the point of the mahalanobis() function in R.
> It looks quite weird to me :-(
Huh?
Try:
> set.seed(42)
> X <- matrix(rnorm(100),25,4)
> S <- var(X)
> x <- rnorm(4)
> mahalanobis(x,rep(1,4),S)
[1] 6.082543
cheers,
Rolf Turner
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