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 [[alternative HTML version deleted]]
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.Onkelinx at 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-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Namens eliza botto Verzonden: maandag 15 april 2013 12:36 Aan: r-help at 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 [[alternative HTML version deleted]] ______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. * * * * * * * * * * * * * D I S C L A I M E R * * * * * * * * * * * * * Dit bericht en eventuele bijlagen geven enkel de visie van de schrijver weer en binden het INBO onder geen enkel beding, zolang dit bericht niet bevestigd is door een geldig ondertekend document. The views expressed in this message and any annex are purely those of the writer and may not be regarded as stating an official position of INBO, as long as the message is not confirmed by a duly signed document.
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.Onkelinx at 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-bounces at r-project.org [mailto:r-help-bounces at r-project.org] Namens eliza botto > Verzonden: maandag 15 april 2013 12:36 > Aan: r-help at 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