On 21.08.2011 12:54, Michael Dewey wrote:
At 18:21 20/08/2011, Uwe Ligges wrote:
On 20.08.2011 19:04, David Winsemius wrote:
On Aug 20, 2011, at 12:32 PM, Uwe Ligges wrote:
[snip original problem]
David,
I think there are some good examples on the help page. What is
missing? What is not clearly explained? If a longer tutorial is
needed, that may be an article for the R Help Desk in The R Journal.
Anybody volunteering?
Uwe
I think the problem is that those of us who do not understand are in
such a state of ignorance that we do not know what it is that we do not
understand. I have resigned myself to the realisation that there are a
very small number of things about R which I shall never understand and
always solve by trial and error and the parameterisation of reshape is
the leading example (closely followed by backslashes). I do not think
the writers of the documentation are at fault here, it is either just
inherently difficult to understand or my cortex is wired up
inappropriately.
In think tha major problem is that stuff like "id" and "time" etc. may
be misleading, if they do not fit to the context. Don't believe I do
things correct right away here. Nevertheless, improving the wording of
the reshape() documentation is not easy at all if we want to be precise.
Maybe we find another volunteer or I find some time to write a short
column for the next issue of The R Journal.
Best wishes,
Uwe
Best,
Uwe
So Hadley wrote an alternate facility ... the reshape package that does
not have a reshape function in it but rather two functions 'melt' and
'cast'.
>
> Your data is all ready "molten", i.e. it is in the long format
(in the terminology of the base reshape function) with identifier values
in each row and a single column of values.
> library(reshape)
> cast(dataframe,A~B)
Using C as value column. Use the value argument to cast to override this
choice
A control sample
1 d0 1e+05 1e+05
2 d1 2e+02 3e+02
3 d2 4e+02 5e+02
Basically the cast formula keeps the LHS variables in the rows and hte
RHD variables get arranges in columns. (For reasons that are unclear to
me the dataframe argument was placed first when using positional
argument passing, unlike most other formula methods in R.)
Michael Dewey
i...@aghmed.fsnet.co.uk
http://www.aghmed.fsnet.co.uk/home.html
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