On 20.08.2011 19:04, David Winsemius wrote:
On Aug 20, 2011, at 12:32 PM, Uwe Ligges wrote:
On 20.08.2011 17:04, Wendy wrote:
Hi all,
I have a data.frame like following
A<-c('d0','d0','d1','d1','d2','d2')
B<-rep(c('control','sample'),3)
C<-c(rep(100000,2),200,300,400,500)
dataframe<-data.frame(A,B,C)
I want to reshape the matrix, so the matrix with 'd0', 'd1' and 'd2'
in rows
and 'control' and 'sample' in columns. Is there a function for doing
this
easily?
See ?reshape
reshape(data=dataframe, idvar="A", timevar="B", direction="wide")
Uwe Ligges
Many people have experienced problems understanding the mechanics of the
base function 'reshape'. If you do not and if do continue to use it, you
would be doing the world a great service by writing a tutorial manual
with a bunch of worked examples. I have never found a tutorial that
clarified how I should use it in the variety of situations where I have
needed it.
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?
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.)
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