Dear R Gurus,
As you probably know, dist calculates the distance between every two rows of
data. What I am interested in is the actual two rows that have the least
distance between them, rather than the numerical value of the distance
itself.
For example, If the minimum distance in the following sample run is d[14],
which is .3826119, and the rows are 4 & 6. I need to find a generic way to
retrieve these rows, for a generic matrix of NRows (in this example NRows=7)
NCols=5
NRows=7
myMat<-matrix(runif(NCols*NRows), ncol=NCols)
d<-dist(myMat)
1 2 3 4 5 6
2 0.7202138
3 0.7866527 0.9052319
4 0.6105235 1.0754259 0.8897555
5 0.5032729 1.0789359 0.9756421 0.4167131
6 0.6007685 0.6949224 0.3826119 0.7590029 0.7994574
7 0.9751200 1.2218754 1.0547197 0.5681905 0.7795579 0.8291303
e<-sort.list(d)
e<-e[1:5] ##Retrieve minimum 5 distances
[1] 14 16 4 18 5
--
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Hi there, I am sure there is a better way to do it, but here is a suggestion: res <- matrix(NA, ncol = 2, nrow = 5) for(i in 1:5) res[i, ] <- which(as.matrix(d) == sort(d)[i], arr.ind TRUE)[1,] res HTH, Jorge On Wed, Jun 9, 2010 at 11:30 PM, Jeff08 <> wrote:> > Dear R Gurus, > > As you probably know, dist calculates the distance between every two rows > of > data. What I am interested in is the actual two rows that have the least > distance between them, rather than the numerical value of the distance > itself. > > For example, If the minimum distance in the following sample run is d[14], > which is .3826119, and the rows are 4 & 6. I need to find a generic way to > retrieve these rows, for a generic matrix of NRows (in this example > NRows=7) > > NCols=5 > NRows=7 > myMat<-matrix(runif(NCols*NRows), ncol=NCols) > > d<-dist(myMat) > > 1 2 3 4 5 6 > 2 0.7202138 > 3 0.7866527 0.9052319 > 4 0.6105235 1.0754259 0.8897555 > 5 0.5032729 1.0789359 0.9756421 0.4167131 > 6 0.6007685 0.6949224 0.3826119 0.7590029 0.7994574 > 7 0.9751200 1.2218754 1.0547197 0.5681905 0.7795579 0.8291303 > > e<-sort.list(d) > e<-e[1:5] ##Retrieve minimum 5 distances > > [1] 14 16 4 18 5 > -- > View this message in context: > http://r.789695.n4.nabble.com/Retrieving-the-2-row-of-dist-computations-tp2249844p2249844.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@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. >[[alternative HTML version deleted]]
Bill.Venables at csiro.au
2010-Jun-10 04:57 UTC
[R] Retrieving the 2 row of "dist" computations
This is a lazy way, and a slightly extravagant way if your memory is limited and
you are dealing with large numbers of rows.
NCols <- 5
NRows <- 7
myMat <- matrix(runif(NCols*NRows), ncol=NCols)
d <- dist(myMat)
dm <- as.matrix(d)
diag(dm) <- Inf
ij <- which(dm == min(dm), arr.ind = TRUE)[1,]
ij
-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Jeff08
Sent: Thursday, 10 June 2010 1:30 PM
To: r-help at r-project.org
Subject: [R] Retrieving the 2 row of "dist" computations
Dear R Gurus,
As you probably know, dist calculates the distance between every two rows of
data. What I am interested in is the actual two rows that have the least
distance between them, rather than the numerical value of the distance
itself.
For example, If the minimum distance in the following sample run is d[14],
which is .3826119, and the rows are 4 & 6. I need to find a generic way to
retrieve these rows, for a generic matrix of NRows (in this example NRows=7)
NCols=5
NRows=7
myMat<-matrix(runif(NCols*NRows), ncol=NCols)
d<-dist(myMat)
1 2 3 4 5 6
2 0.7202138
3 0.7866527 0.9052319
4 0.6105235 1.0754259 0.8897555
5 0.5032729 1.0789359 0.9756421 0.4167131
6 0.6007685 0.6949224 0.3826119 0.7590029 0.7994574
7 0.9751200 1.2218754 1.0547197 0.5681905 0.7795579 0.8291303
e<-sort.list(d)
e<-e[1:5] ##Retrieve minimum 5 distances
[1] 14 16 4 18 5
--
View this message in context:
http://r.789695.n4.nabble.com/Retrieving-the-2-row-of-dist-computations-tp2249844p2249844.html
Sent from the R help mailing list archive at Nabble.com.
______________________________________________
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.
Hey, The code definitely works, but I may need a more elegant way to do it. Rather than 5 rows, the full data contains 829 rows, so instead of d of length 10, d will be of length 343206. Jorge Ivan Velez wrote:> > Hi there, > > I am sure there is a better way to do it, but here is a suggestion: > > res <- matrix(NA, ncol = 2, nrow = 5) > for(i in 1:5) res[i, ] <- which(as.matrix(d) == sort(d)[i], arr.ind > TRUE)[1,] > res > > HTH, > Jorge > > > On Wed, Jun 9, 2010 at 11:30 PM, Jeff08 <> wrote: > >> >> Dear R Gurus, >> >> As you probably know, dist calculates the distance between every two rows >> of >> data. What I am interested in is the actual two rows that have the least >> distance between them, rather than the numerical value of the distance >> itself. >> >> For example, If the minimum distance in the following sample run is >> d[14], >> which is .3826119, and the rows are 4 & 6. I need to find a generic way >> to >> retrieve these rows, for a generic matrix of NRows (in this example >> NRows=7) >> >> NCols=5 >> NRows=7 >> myMat<-matrix(runif(NCols*NRows), ncol=NCols) >> >> d<-dist(myMat) >> >> 1 2 3 4 5 6 >> 2 0.7202138 >> 3 0.7866527 0.9052319 >> 4 0.6105235 1.0754259 0.8897555 >> 5 0.5032729 1.0789359 0.9756421 0.4167131 >> 6 0.6007685 0.6949224 0.3826119 0.7590029 0.7994574 >> 7 0.9751200 1.2218754 1.0547197 0.5681905 0.7795579 0.8291303 >> >> e<-sort.list(d) >> e<-e[1:5] ##Retrieve minimum 5 distances >> >> [1] 14 16 4 18 5 >> -- >> View this message in context: >> http://r.789695.n4.nabble.com/Retrieving-the-2-row-of-dist-computations-tp2249844p2249844.html >> Sent from the R help mailing list archive at Nabble.com. >> >> ______________________________________________ >> 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. >> > > [[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. > >-- View this message in context: http://r.789695.n4.nabble.com/Retrieving-the-2-row-of-dist-computations-tp2249844p2249900.html Sent from the R help mailing list archive at Nabble.com.