[R] Select the last rows of when specific conditions are met.

[Jessica Streicher]

I really don't understand what you want to achieve and how your data presents itself.

You have several combinations of trial/subject which are unique?
There is a variable for each such combination that you want to test against (tt)?
In addition you have data on each such combination (several sets with 17 columns ) ?
or each column is a subject and each row a trial or something along those lines?

On 01.11.2012, at 16:18, mardijk wrote:

> Hello,
> 
> As I am new with R I am completely stuck in resolving a, no doubt, easy
> problem.
> 
> I have a dataset with an enormous amount of rows and 17 columns. I need to
> know per trial and subject number if another variable (tt) exceeds a
> maximum. If this is true than the last 5000 rows of that specific trial for
> that subject number needs to be deleted. 
> 
> But I am completely stuck on how to do so. After various attempts I have
> finally come up with the following (which obviously does not work).
> 
> 
> if (dat["tt"]>6000
> ){
> 	return(
> 	tail(dattest[,c("Trial", "Subj" )],n=5000) <- NA
> }
> 
> Can anybody explain what I need to do?
> 
> Thank you so much!
> 
> 
> 
> 
> 
> 
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