Presumably --- based on the question she actually *asked* --- she does
NOT have the coordinates of the stations; only the distance matrix.
I believe that the following will do the job: Let M be the distance matrix.
diag(M) <- Inf
nn5 <- apply(M,1,function(x){((1:length(x))[order(x)])[1:5]})
Check:
require(spatstat)
set.seed(42)
X <- runifpoint(44)
M <- crossdist(X,X)
diag(M) <- Inf
nn5 <- apply(M,1,function(x){((1:length(x))[order(x)])[1:5]})
plot(X)
plot(X[1],add=TRUE,chars=20,cols="red")
plot(X[nn5[,1]],add=TRUE,chars=20,cols="blue")
# Looks right to me.
cheers,
Rolf Turner
On 15/04/13 22:42, ONKELINX, Thierry wrote:
Dear Eliza,
If you have the coordinates of the stations you can use the nnwhich() function
from the spatstat package.
Best regards,
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium
+ 32 2 525 02 51
+ 32 54 43 61 85
thierry.onkel...@inbo.be
www.inbo.be
To call in the statistician after the experiment is done may be no more than
asking him to perform a post-mortem examination: he may be able to say what the
experiment died of.
~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data.
~ Roger Brinner
The combination of some data and an aching desire for an answer does not ensure
that a reasonable answer can be extracted from a given body of data.
~ John Tukey
-----Oorspronkelijk bericht-----
Van: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] Namens
eliza botto
Verzonden: maandag 15 april 2013 12:36
Aan: r-help@r-project.org
Onderwerp: [R] nearest stations in distance matrix
Dear R-user,
Is there a way in R to locate the nearest 5 indices to a station, based on
distances in a distance matrix. In other words i want to have nearest stations
based on the distances in the matrix. The distance matrix, i have, has
dimension 44*44.
Thankyou very much in advance
Elisa
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