Use %in% instead of ==, and string conditions together with &.
HTH,
Andy
> From: CG Pettersson
>
> 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"))
>
> 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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