On Nov 4, 2010, at 8:28 AM, Ramsvatn Silje wrote:
Hello,
I have tried to find this out some other way, but unsuccessful I
have to
try this list.
I assume this should be quite simple.
I have a dataset with 4 columns, "Sample_no", "Species", "Nitrogen",
"Carbon" in csv format. In the species column I have many different
species with varying number of obs per species
Eg
"Sample_no" "Species" "Nitrogen" "Carbon"
1 Cod 15.2 -19.0
2 Haddock 14.8 -20.2
3 Cod 15.6 -18.5
4 Cod 13.2 -20.1
5 Haddock 14.3 -18.8
Etc..
And I want to calculate, mean, standard dev etc per species for the
observations "Nitrogen" and "Carbon". And later do plots and stats
with
the different species. I will in the end have many species, so need
it to
be "automatic" I can't enter code for every species separate.
http://finzi.psych.upenn.edu/R/library/prettyR/html/brkdn.html
http://finzi.psych.upenn.edu/R/library/Hmisc/html/describe.html
e.g
library(Hmisc)
with( dfrm, describe( ~Species) )
I think you could also probably do lapply(split(dfrm, dfrm$species),
describe)
the Hmisc::describe function is especially good at first examining a
vector and applying the appropriate methods to the type of data. There
are several other packages with different describe functions.
And there are several other packages such as doBy and plyr that will
offer other concise methods for doing your by-category statistics.
--
David.
Can anyone help me with this? Or if this is the wrong list to sendt
this
question to, where do I send it?
Thank you very much in advance.
Best regards
Silje Ramsvatn
PhD-candidate
University of Tromsø
Norway
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