I'm trying to use tapply to output means and SD or SE for my data but
seem to be limited by how many times I can subset it. Here's a snippet
of my data
> stems353[1:10,]
Time DataSource Plot Elevation Aspect Slope Type Species
SizeClass Stems
1 Modern Cameron 70F221 1730 ESE 20 Conifer ABCO
Class1 3
2 Modern Cameron 70F221 1730 ESE 20 Conifer ABMA
Class1 0
3 Modern Cameron 70F221 1730 ESE 20 Hardwood ACMA
Class1 0
4 Modern Cameron 70F221 1730 ESE 20 Hardwood AECA
Class1 0
5 Modern Cameron 70F221 1730 ESE 20 Hardwood ARME
Class1 0
6 Modern Cameron 70F221 1730 ESE 20 Conifer CADE
Class1 15
7 Modern Cameron 70F221 1730 ESE 20 Hardwood CELE
Class1 0
8 Modern Cameron 70F221 1730 ESE 20 Hardwood CONU
Class1 0
9 Modern Cameron 70F221 1730 ESE 20 Conifer JUCA
Class1 0
10 Modern Cameron 70F221 1730 ESE 20 Conifer JUOC
Class1 0
I'd like to see means/SD of "Stems" stratified by "Species", "Time" and
"SizeClass". I can get R to give me this for means by species:
> tapply(stems353$Stems, stems353$Species, mean)
ABCO ABMA ACMA AECA
ARME CADE CELE
0.7305240793 0.8569405099 0.0003541076 0.0010623229 0.0017705382
0.4684844193 0.0063739377
CONU JUCA JUOC LIDE
PIAL PICO PIJE
0.0017705382 0.0003541076 0.0959631728 0.0138101983 0.3905807365
1.5651558074 0.2315864023
PILA PIMO PIMO2 PIPO
PISA POTR PSME
0.1774079320 0.1880311615 0.0311614731 0.6735127479 0.0237252125
0.0506373938 0.2000708215
QUCH QUDO QUDU QUKE
QULO QUWI Salix
0.0474504249 0.1203966006 0.0000000000 0.2071529745 0.0003541076
0.0548866856 0.0003541076
SEGI TSME
0.0021246459 0.5017705382
>
but I really need to see each species by SizeClass and Time so that each
value would be labeled something like "ABCOSizeClass1TimeModern".
Adding 2 variables to the function doesn't seem to work
> tapply(stems353$Stems, stems353$Species, stems353$SizeClass,
stems353$Time, mean)
Error in match.fun(FUN) :
'stems353$SizeClass' is not a function, character or symbol
I've already created proper subsets for each of these groups, e.g. one
subset is called "stems353ABCO1" and I can run analyses on this. But,
trying to extract means straight from those subsets doesn't seem to work
> mean(stems353ABCO1)
[1] NA
Warning message:
In mean.default(stems353ABCO1) :
argument is not numeric or logical: returning NA
>
Thanks,
Chris Dolanc
--
Christopher R. Dolanc
PhD Candidate
Ecology Graduate Group
University of California, Davis
Lab Phone: (530) 752-2644 (Barbour lab)
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