[R] melting a list: basic question

baptiste auguie ba208 at exeter.ac.uk
Fri Jul 25 16:49:36 CEST 2008

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  

> 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 Auguié

School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,

Phone: +44 1392 264187


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