[R] subsetting a data set

[Petr Pikal]

Sorry, I did not notice that in your case Max is not a function but 
your data. So probably

by(Max[, your.columns], list(Max$status), summary)

is maybe what you want.
HTH
Petr


On 8 Sep 2006 at 10:31, Petr Pikal wrote:

From:           	"Petr Pikal" <petr.pikal at precheza.cz>
To:             	"Graham Smith" <myotisone at gmail.com>, r-help at stat.math.ethz.ch
Date sent:      	Fri, 08 Sep 2006 10:31:12 +0200
Priority:       	normal
Subject:        	Re: [R] subsetting a data set

> Hi
> 
> 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), max)
> 
> 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.
> 
> HTH
> Petr
> 
> 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]]
> > 
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html and provide commented,
> > minimal, self-contained, reproducible code.
> 
> Petr Pikal
> petr.pikal at precheza.cz
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html and provide commented,
> minimal, self-contained, reproducible code.

Petr Pikal
petr.pikal at precheza.cz