similar to: Write lower half of distance matrix only

I'm trying to perform a mantel test that ignores specific pairs in my distance matrices. The reasoning is that some geographic distances below a certain threshold suffer from spatial autocorrelation, or perhaps ecological relationships become less relevant that stochastic processes above a certain threshold. The problem is that I can't find a way to do it. If I replace values in either or

Hi, Am wanting to save the summary of a PCA to file. Have tried: > write.table(summary(PCA), file="PCAvar.txt", sep="\t") but receive: Error in as.data.frame.default(x[[i]], optional = TRUE, stringsAsFactors = stringsAsFactors) : cannot coerce class "summary.princomp" into a data.frame What am I doing wrong? Thanks -- View this message in context:

Dear UseRs, i want to apply mantel test by comparing a list of 124 distance matrices with a reference distance matrix "q". The list of distance matrices was created by the following command.. u<-lapply(el, function(x) dist(x)) where "el" is a data frame of 75 columns and 124 rows. Therefore, the list of distances matrices, made out of it should have 75 elements each

My objective is to look at differences in two species of fish from morphometric measurements. My morphometric measurements are head length, eye diameter, snout length, and measurements from tail to each fin. I want to use discrimanant function analyis to determine if there are differences between the two species. I am familiar with R but new to discrimannt function analysis. I want to learn

Hi there, I would like to find a more efficient way of permuting the rows and columns of a symmetrical matrix that represents ecological or actual distances between objects in space. The permutation is of the type used in a Mantel test. Specifically, the permutation has to accomplish something like this: Original matrix addresses: a11 a12 a13 a21 a22 a23 a31 a32 a33 Example

Hi, i'm looking to test if two distance matrices are statistically different from each others. These two matrices have been computed on the same set of data (several population samples) 1. using a particular genetic distance 2. weighting that genetic distance with an extra factor (we can look at this as one set is computed before applying a treatment and the second one after applying

I would like to perform partial mantel tests on only within group values, with "between group" values assigned to NA. This is possible in package ncf partial.mantel.test, however this sues a different permutation to that used in ecodist.ecodist will not accept data with NA values, returning a "matrix is not square error. is it possible to perform this test in ecodist? many thanks

Hi, I'm wanting to do a PCA on some data which is comprised of two different groups (to see how well the groups are discriminated). Is there a way to change the colour of the datapoints in a biplot so that I can easily see which group is which (eg objects 1-100, red, 101-200, black). Might be simple, but I'm new to R and can't seem to find how to do this. Thanks. Paul -- View this

Dear R users, I am having a problem performing the mantel test (both with functions mantel {vegan} and mantel.test {ape}) due to I believe the presence of NAs on my distance matrices, which look like e.g.: NA 1 2 1 2 3 NA 4 5 6 and 1 1 2 2 3 4 5 6 7 8 Would any of you have a solution for that? Thank you for much for your help! Marcia Rocha -- View this message in

Hi, my name is Gastón. I just read a question, made by Walter Durka, about a nonparametric discriminant analysis. It wasn´t any answer, and I was wondering if at this moment there is one. I have the same problem as W. Durka. I´m trying to classify and to cross-validate samples of three tunicates species based on morphometric data and to identify the variables that best discriminate between

Dear R'ers, When I used S-plus i wrote a small program for a Mantel-Haenszel test for trend (I think it worked). Unfortunately I can't get it working in R. It appears as if my use of 'el' is the problem but I can't sort it out. Error in apply(array, c(, 2, 3), function(el) el * 1:s) : argument is missing, with no default Further down in the program I use 'el'

Hello, Is there an easy function for switching list to matrix. My list is of genetic distances between species pairs: A A 0 A B .5 A C .25 B C .5 and I want a distance matrix such as: A B C A 0 .5 .25 B .5 0 .5 C .25 .5 0 for use in a mantel test. Thank you for the help! cheers, charlie -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Charles G. Willis Department of Organismic

Hello, I have some satellite tag time-at-depth (TAD) frequency data that I would like some help with. The data was transmitted via satellite as percent time spent in each of 7 depth bins (0m, 0-1m, 1-10m, 10-50m etc.), binned over 6-hour intervals. I categorized each row of data corresponding to a date and time into summer vs. winter, and day vs. night, and then summed and averaged the given

Dear Dr.Goslee and anyone may intrested in matrix manipulate, I am using your ecodist to do mantel and partial mantel test, I have locality data and shape variation data, and the two distance matrixs are given as belowings. When I run the analysis, it is always report that the matrix is not square, but I didn't know what's wrong with my data. Would you please help me on this. I am quite

Hello, I performed a Mantel test and plotted communitiy similarities. I would like to add a least square line. I thought about using abline taking as slope the r-statistic of the Mantel test and calculating the y-intercept analytically. Is this method correct? Is there any function for this calculation? Thank you -- View this message in context:

Hello! It is not really linked to R, but can somebody explain me why we sometimes make a mantel test directly for to distance matrices and sometimes we first make a gradient analysis and then a mantel test between the axis? Thank you -- View this message in context: http://www.nabble.com/Mantel-test-tp25439984p25439984.html Sent from the R help mailing list archive at Nabble.com.

Dear all, Does anyone knows why the results of a BIOENV (PRIMER v. 6.1.15) are diferent of the bioenv() + mantel() in vegan? Not the spearman correlation, indeed the pseudo-p value. I know that the approach bioenv() + mantel() is biased. So, how the BIOENV (PRIMER) ends with larger p values (permutated). Acctualy how the permutation test in BIOENV (PRIMER) is conducted. The user guide does not

Hi all, Does anyone know if an R function for the Mantel-Haenszel chi-square for a 2x2 table exists? I’ve also seen it called the randomization Q statistic. Note that I’m not looking for the Cochran-Mantel-Haenszel…I did see that out there as cmh.test. Thanks in advance, Jeff Internal Virus Database is out-of-date. Checked by AVG Free Edition. 11:27 AM [[alternative HTML version

I would like to know how to run a partial mantel test controlling for spatial autocorrelation and correlation with other environmental variables. It seems that with function included in vegan for partial mantel test I can only test for the relationship between two variables controlling for the effect of a third one. Thanks a lot Alexandra --- Lic. Alexandra Sapoznikow Centro Nacional

Dear Sir/ Madam, I would like to ask you about mantel test in R. In ade4 package, if I want to use mantel.rtest, I get error massage "Object of class to "dist" expected". As I already have two dissimilarity matrices, shall I again compute distance measure using this function? If not, could you please let me know which function/command I can use to do? Thank you very much in