[R] transpose dataset to PC-ORD?

From: Daniel Gruner <dsgruner_at_ucdavis.edu>
Date: Wed 24 May 2006 - 05:36:44 EST


I need to take a species-sample matrix and transpose it to the format used by PC-ORD for analysis. Unfortunately, the number of species is very large (>5000), and so this operation cannot be performed simply in an application like Excel, which has a 255 column limit. So, I wrote relatively simple code in R that I hoped would do this
(appended below). But there are glitches.

The format needed for PC-ORD (where "NA" shows an empty cell):



2 cells in first row indicate number of samples (rows), the second column indicates number of species (columns), the third row indicates variable type (Q = quantitative), and the fourth row shows column headers (species names). So, one can create a transposable matrix in a spreadsheet where 5000+ species are the rows:


It is important that the data file written out is totally clean and ready to go for PC-ORD, because I cannot open and edit it in a spreadsheet. However, the code performs the transpose operation and writes the file, but now the former row IDs are the first row in the new file (NA,1,2,3), and the 4 leading spaces are "X, X.1, X.2, X.3". I'd like to delete the first row and delete the first 4 values of column1, without deleting the column.




I have tried various tricks that I will not list/belabor here
(various col.names, row.names, header, Extract, etc commands). Any
further hints on code that will either stop R from adding these, or strip them at the end?

(PS, yes, I can learn how to my multivariate analyses in R and skip
PC-ORD, but I am time limited on this one, and it seems that this code could be very useful in numerous ways)

Many thanks for the help,
Dan Gruner
(Windows XP, R vers2.2)

##transpose datasets to convert to PC-ORD format

data<-read.csv("data.csv", header=TRUE, as.is=T,

    strip.white=T, na.strings="NA")
data.trans <- t(data)
write.csv(data.trans, file = "datatransp.csv",

    quote = F, na = "")

Daniel S. Gruner, Postdoctoral Scholar
Bodega Marine Lab, University of California -- Davis PO Box 247, 2099 Westside Rd
Bodega Bay, CA 94923-0247
(o) 707.875.2022 (f) 707.875.2009 (m) 707.338.5722
email: dsgruner_at_ucdavis.edu
http://www.bml.ucdavis.edu/facresearch/gruner.html http://www.hawaii.edu/ant/

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