[R] Extracting only odd columns from a matrix

[Bill.Venables at csiro.au]

Xonly <- XY[, grep("^X", dimnames(XY)[[2]])]

 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Nixon, Matthew
Sent: Thursday, 10 March 2011 12:20 AM
To: r-help at R-project.org
Subject: [R] Extracting only odd columns from a matrix

Hi,

This might seem like a simple question but at the moment I am stuck for ideas. The columns of my matrix in which some data is stored are of this form:

X1     Y1     X2     Y2     X3     Y3     ...     Xn     Yn

with n~100. I would like to look at just the X values (i.e. odd column numbers). Is there an easy way to loop round extracting only these columns?

Any help would be appreciated.

Thank you.
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