Hello all,

A friend recently brought to my attention that vector assignment actually
recreates the entire vector on which the assignment is performed.

So for example, the code:
x[10]<- NA # The original call (short version)

Is really doing this:
x<- replace(x, list=10, values=NA) # The original call (long version)
# assigning a whole new vector to x

Which is actually doing this:
x<- `[<-`(x, list=10, values=NA) # The actual call


Assuming this can be explained reasonably to the lay man, my question is,
why is it done this way ?
Why won't it just change the relevant pointer in memory?

On small vectors it makes no difference.
But on big vectors this might be (so I suspect) costly (in terms of time).


I'm curious for your responses on the subject.

Best,
Tal



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