[R] array vs matrix vs dataframe?

[Duncan Murdoch]

On 10/1/2006 7:02 PM, r user wrote:
> What is the difference among an array, a dataframe and
> a matrix?
> 
> Why is the size of a dataframe so much larger? (see
> example below)

I forgot to mention:  there will be very little difference in 2.4+; the 
row names were a problem in earlier releases, but Brian Ripley fixed that:

 > a<-c(rep(1:1000000,1))
 > b<-c(rep(1:1000000,1))
 > c1<-cbind(a,b)
 > cdf<-as.data.frame(cbind(a,b))
 > cm<-as.matrix(cbind(a,b))
 >
 > object.size(a)/1000000
[1] 4.000024
 > object.size(b)/1000000
[1] 4.000024
 > object.size(c1)/1000000
[1] 8.000296
 > object.size(cdf)/1000000
[1] 8.000448
 > object.size(cm)/1000000
[1] 8.000296

(These are in a recent release candidate of 2.4.0.)

Duncan Murdoch