[R] melting a list: basic question

[baptiste auguie]

Dear list,


I'm trying to use the reshape package to perform a merging operation  
on a list of data.frames as illustrated below,

> a <- 1:10
> example <- list( data.frame(a=a, b=sin(a)),  data.frame(a=a,  
> b=cos(a)) )
>
> melt(example, id = a)

this produces the desired result, where the data.frames have been  
coerced into one with a common identifier variable "a". However, it  
seems that if "a" is of mode numeric it is not recognized as an id  
variable,

> a <- as.numeric(1:10)
>
> example <- list(data.frame(a=a, b=sin(a)), data.frame(a=a, b=cos(a)))
>
> melt(example, id = a) # this does not use a as an id variable

I'm very new to the reshape package, any pointer would be greatly  
appreciated. I first tried several combinations of merge, do.call,  
sapply,... but without success.

Many thanks,

baptiste


   _____________________________

Baptiste Auguié

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK

Phone: +44 1392 264187

http://newton.ex.ac.uk/research/emag