[R] Subsetting data systematically

[Peter Alspach]

Tena koe Nate

You can use the fact that R recycles.  If yourData is a dataframe, then (as examples):

yourData[c(TRUE,FALSE),] will give you every second row, starting with the first.  Similarly,
yourData[c(FALSE,TRUE,FALSE),] will give every third row, starting with the second; and
yourData[c(TRUE, rep(FALSE,19)),] will give every twentieth row, starting with the first.

There's also seq().

HTH ....

Peter Alspach.

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of gibberish
> Sent: Thursday, 23 June 2011 11:05 a.m.
> To: r-help at r-project.org
> Subject: [R] Subsetting data systematically
> 
> I would like to subset data from a larger dataset and generate a
> smaller
> dataset.  However, I don't want to use sample() because it does it
> randomly.
> I would like to take non-random subsamples, for example, every 2nd
> number,
> or every 3rd number.  Is there a procedure that does this?
> 
> Thanks, Nate
> 
> --
> View this message in context: http://r.789695.n4.nabble.com/Subsetting-
> data-systematically-tp3618516p3618516.html
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