similar to: Better way to find distances between points in a set?

Displaying 20 results from an estimated 6000 matches similar to: "Better way to find distances between points in a set?"

2008 Dec 10
1
subset point data set by distance ranges
Greetings I'm using R 2.8 with recent (last month) versions of the packages I need to use at present. I'm interested in examining hierarchical spatio-temporal patterns in a data set. The data consist of 94 points (X, Y, UTM coordinates) at which catch rates for a fish were recorded and there are also estimates of prey available for these fish at the same locations.
2008 Dec 22
2
How can I avoid nested 'for' loops or quicken the process?
Hi All, I'm still pretty new to using R - and I was hoping I might be able to get some advice as to how to use 'apply' or a similar function instead of using nested for loops. Right now I have a script which uses nested for loops similar to this: i <- 1 for(a in Alpha) { for (b in Beta) { for (c in Gamma) { for (d in Delta) { for (e in Epsilon) { Output[i] <-
2008 Feb 01
3
Phase Shift
Is there any implementation in R for finding the phase shift between two continuous signals. I would like to find the average phase shift for tow signals over two years. thanks Stephen -- Let's not spend our time and resources thinking about things that are so little or so large that all they really do for us is puff us up and make us feel like gods. We are mammals, and have not exhausted
2010 Jan 23
2
About LU decomposition in R
Hi, How can I find and download a function in R to do the LU decompostion for finding the upper and lower triangular matrix.  Thank you so much. Joe ___________________________________________________ 您的生活即時通 - 溝通、娛樂、生活、工作一次搞定! [[alternative HTML version deleted]]
2010 Nov 13
2
how to store a vector of vectors
Hi, I'm trying to write a function to determine the euclidean distance between x (one point) and y (a set of n points). How should I pass y to the function? Until now, I used a matrix like that: | [,1] [,2] [,3] [1,] 0 2 1 [2,] 1 1 1 | Which would pass the points (0,2,1) and (1,1,1) to that function. However, when I pass x as a normal (column) vector,
2008 Nov 06
2
replacing characters in formulae / models
Dear all, How can I replace text in objects that are of class "formula"? y="a * x + b" class(y)="formula" grep("x",y) y[1] Suppose I would like to replace the "x" by "w" in the formula object "y". How can this be done? Somehow, the methods that can be used in character objects do not work 1:1 in formula objects... Many
2008 Nov 14
1
configuring graphics device in Linux
greetings, i'm trying plot() from Owen's _The R Guide_ and having trouble with being able to view the result. the Graphics Device 2 draws an image i can only see the top part of and when i try to manipulate the window to see the image, the window then says: "...ure margins too lar..." in large letters. i guess it says something about picture margins too large. i'm not sure
2005 Jul 06
1
Help: Mahalanobis distances between 'Species' from iris
Dear R list, I'm trying to calculate Mahalanobis distances for 'Species' of 'iris' data as obtained below: Squared Distance to Species From Species: Setosa Versicolor Virginica Setosa 0 89.86419 179.38471 Versicolor 89.86419 0 17.20107 Virginica 179.38471 17.20107 0 This distances above were obtained with proc
2008 Dec 11
3
Resampling physiological data using R?
Dear all R users, I am going to use R to process some of my physiological data about eye. The problem is the recording machine does not sample in a reliably constant rate: the time intervals between data sampled can vary from 9msec to ~120msec, while most around in the 15-30msec range. The below is a fraction of a single data file of a trial: Time CursorX CursorY Pupilsize 1811543 -1 -1 -1
2006 Aug 31
2
Wish: keep names in mapply() result
Hello! I have noticed that mapply() drops names in R 2.3.1 as well as in r-devel. Here is a simple example: l <- list(a=1, b=2) k <- list(1) mapply(FUN="+", l, k) [1] 2 3 mapply(FUN="+", l, k, SIMPLIFY=FALSE) [[1]] [1] 2 [[2]] [1] 3 Help page does not indicate that this should happen. Argument USE.NAMES does not have any effect here as it used only in a bit special
2011 Feb 02
2
Help me apply mapply
Hello all I would like to ask your help use mapply. I have a function called findCell that takes two arguments(x,sr) where x is a vector of size two (e.g x<-c(2,3) and sr is a matrix. I would like to call many times the findCell function (thus I need mapply) for different x inputs but always for the same sr. as x is a vector of size two (two cells) I want to pass inside inside the following
2009 Jan 06
5
Using apply for two datasets
I can run one-sample t-test on an array, for example a matrix myData1, with the following apply(myData1, 2, t.test) Is there a similar fashion using apply() or something else to run 2-sample t-test with datasets from two groups, myData1 and myData2, without looping? TIA, Gang
2013 Dec 06
2
Using assign with mapply
I have a data frame whose first colum contains the names of the variables and whose second colum contains the values to assign to them: : kkk <- data.frame(vars=c("var1", "var2", "var3"), vals=c(10, 20, 30), stringsAsFactors=F) If I do : assign(kkk$vars[1], kkk$vals[1]) it works : var1 [1] 10 However, if I try with mapply
2006 Jul 20
2
Timing benefits of mapply() vs. for loop was: Wrap a loop inside a function
List: Thank you for the replies to my post yesterday. Gabor and Phil also gave useful replies on how to improve the function by relying on mapply rather than the explicit for loop. In general, I try and use the family of apply functions rather than the looping constructs such as for, while etc as a matter of practice. However, it seems the mapply function in this case is slower (in terms of CPU
2008 Jun 13
1
Output of silhouette (cluster package)
Dear R users, I am mailing you about the graphical output of silhouette (cluster package) From the example of silhouette in help(silhouette): > ar <- agnes(ruspini) > si3 <- silhouette(cutree(ar, k = 5), # k = 4 gave the same as pam() above + daisy(ruspini)) > plot(si3, nmax = 80, cex.names = 0.5) from which one may conclude that group 1 is composed by
2006 Sep 03
3
Merge list to list - as list
Dear all, #Last week, I asked about merge x and y as list. #Now I have a dataset with list of list like: x <- list(list(matrix(1:20, 5, 4),matrix(1:20, 5, 4)), list(matrix(1:20, 5, 4),matrix(1:20, 5, 4))) y <- list(list(c(1, -1, -1, 1, 1),c(1, 1, -1, -1, -1)), list(c(1, 1, 1, 1, 1),c(1, 1, -1, 1, -1))) x y #I need merge x and y, I have tried with list.uni <-
2004 Jun 01
2
mysql passwd backend
Hey, I'm trying to use the mysql plugin with Samba 3.0.2 and am running into problems with the password storing aspect of the equation. Specifically, here is how I have the smb.conf file setup: [global] workgroup = SRS netbios name = DustPuppy passdb backend = mysql:mysql mysql:mysql host = localhost mysql:mysql user = samba
2012 Nov 15
1
bug with mapply() on an S4 object
Hi, Starting with ordinary vectors, so we know what to expect: > mapply(function(x, y) {x * y}, 101:106, rep(1:3, 2)) [1] 101 204 309 104 210 318 > mapply(function(x, y) {x * y}, 101:106, 1:3) [1] 101 204 309 104 210 318 Now with an S4 object: setClass("A", representation(aa="integer")) a <- new("A", aa=101:106) > length(a)
2012 Mar 12
2
mapply & assign to generate functions
Hi, I have a problem that I'm finding a bit tricky. I'm trying to use mapply and assign to generate curried functions. For example, if I have the function divide divide <- function(x, y) { x / y } And I want the end result to be functionally equivalent to: half <- function(x) divide(x, 2) third <- function(x) divide(x, 3) quarter <- function(x) divide(x, 4) But I want
2003 Oct 14
3
mapply() gives seg fault
Hello everybody. I've been experimenting with mapply(). Does anyone else have problems with: R> mapply(rep,times=1:4, MoreArgs=42) (I get a seg fault). robin R> R.version _ platform powerpc-apple-darwin6.6 arch powerpc os darwin6.6 system powerpc, darwin6.6 status beta major 1 minor 8.0 year 2003 month 10 day 02 language R >