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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