[R] subsetting a data set

Petr Pikal petr.pikal at precheza.cz
Fri Sep 8 10:31:12 CEST 2006


I am not sure if your Max is the same as max so I am not sure what 
you exactly want from your data. However you shall consult ?tapply, 
?by, ?aggregate and maybe also ?"[" together with chapter 2 in intro 
manual in docs directory.

aggregate(data[, some.columns], list(data$factor1, data$factor2), 

will give you maximum for specified columns based on spliting the 
data according to both factors

Also connection summary with max is not common and I wonder what is 
your output in this case. I believe that there are six same numbers. 
However R is case sensitive and maybe Max does something different 
from max. In my case it throws an error.


On 8 Sep 2006 at 8:06, Graham Smith wrote:

Date sent:      	Fri, 8 Sep 2006 08:06:16 +0100
From:           	"Graham Smith" <myotisone at gmail.com>
To:             	r-help at stat.math.ethz.ch
Subject:        	[R] subsetting a data set

> I have a data set called GQ1, which has 20 variables one of which is a
> factor called Status at thre levels "Expert", "Ecol" and "Stake"
> I have managed to evaluate some of the data split by status using
> commands like:
> summary (Max[Status=="Ecol"])
> BUT how do I produce  asummary for Ecol and Expert combined, the only
> example I can find suggsts I could use
> summary (Max[Status=="Ecol"& Status=="Expert"]) but that doesn't work.
> Additionally on the same vein, if I cannot work out how to create a
> new data set that would contain all the data for all the variables but
> only for the data where Status = Ecol, or where status equalles Ecol
> and Expert.
> I know this is yet again a very simple problem, but I really can't
> find the solution in the help or the books I have.
> Many thanks,
> Graham
>  [[alternative HTML version deleted]]
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Petr Pikal
petr.pikal at precheza.cz

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