In C, a fast way to slice a vector?

Saptarshi,
I know of two alternatives you can use to do fast extraction of  
consecutive subsequences of a vector:

1) Fast copy:  The method you mentioned of creating a memcpy'd vector
2) Pointer management: Creating an externalptr object in R and manage  
the start and end of your data

If you are looking for a prototyping environment to try, I recommend  
using the IRanges and Biostrings packages from the Bioconductor  
project. The IRanges package contains a function called subseq for  
performing 1) on all basic vector types (raw, logical, integer, etc.)  
and Biostrings package contains a subseq method on an externalptr  
based class that implements 2.

I was going to lobby R core members quietly about adding something  
akin to subseq from IRanges into base R since it is extremely useful  
for all long vectors and could replace all a:b calls with a <= b in R  
code, but this publicity can't hurt.

Here is an example:

In C, a fast way to slice a vector?

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