[R] How to get the n (number of observations) per conditional group

[John Kane]

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--- On Thu, 8/13/09, Dax <rienk.doetjes at gmail.com> wrote:

> From: Dax <rienk.doetjes at gmail.com>
> Subject: [R] How to get the n (number of observations) per conditional group
> To: r-help at r-project.org
> Received: Thursday, August 13, 2009, 10:11 AM
> Hello all,
> 
> I have a huge data set that I'm cleaning up a bit. I am
> extracted the
> means per condition, but also need to get the n. Strangely
> enough I am
> unable to find a function that could actually pull this
> off. I am
> unable to use replications or count the rows using nrow.
> 
> What I am trying to obtain is the number of observations
> fitting
> something along the lines of
> "data$total[data$spp==1&data$gyro==1&data
> $salinity==0&data$day==i]"
> 
> Can anyone help me?
> 
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> 


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