[R] Subsetting with more than one criteria

[Petr Pikal]

Hi

On 29 Oct 2004 at 12:00, CG Pettersson wrote:

> Hello all!
> 
> I have been using R for two years, but still have trivial problems.
> For the moment, I run R1.9.1 on a W2k computer.
> 
> I work with a dataset from a variety evaluation project. Every year 25
> varieties have been tested. The tested cultivars have been the same
> each year in all trials, but some have changed over the three year
> period. Now I want to do some calculations and plotting on subsets.
> The structure looks like this:
> 
> Year	ADB	Block	Vcode	Variety	Yield	Protein			
> 2002	SW0024	1	20226	Denise	5843	12.8....	
> 2002	SW0024	1	9865	Astoria	6729	11.4	
> 2002	SW0024	1	9622	Barke	6121	12	
> 2002	SW0024	1	9604	Cecilia	5579	12.7	
> 2002	SW0024	1	20223	Granta	5591	11.6	
> 2002	SW0024	1	20222	Class	5591	11.7	
> 2002	SW0024	1	9922	Wiking	5744	12.5
> 2002	SW0024	1	20103	Vortex	5863	10.6
> .
> .
> And so on both down and sideways.
> Three years and four trials with three replicats each gives 900 lines.
> 
> 
> How do I use several criteria to subset this?
> 
> Ast <- subset(data, Variety == "Astoria") 
> 
> works fine giving back the 36 lines where Astoria appears.
> But how do I pick two (or more) varieties? AND picking one (or two)
> years?
> 
> Everything I have tried results in rubbish, like:
> 
> AstBark <- subset(data, Variety == c("Astoria","Barke"))

subset(data, subset = (Variety %in% c("Astoria", "Barke")))

should work. There has to be logical expression subset in subset() 
function which gives you correct answer. 

HTH
Cheers
Petr

> 
> which seems to work but gives back 19 and 18 lines of the varieties 
> 
> respectively. There exists 36 of each....
> 
> Thanks
> 
> /CG
> 
> 
> CG Pettersson, MSci, PhD Stud.
> Swedish University of Agricultural Sciences
> Dep. of Ecology and Crop Production. Box 7043
> SE-750 07 Uppsala
> 
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Petr Pikal
petr.pikal at precheza.cz