[R] Extracting a range of elements from a vector
Gabor Grothendieck
ggrothendieck at gmail.com
Sat Aug 25 14:25:37 CEST 2007
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On 8/25/07, Otis Laws <msc22ojl at cs.bham.ac.uk> wrote:
> Dear R users
>
> I am R newbie creating a function that implements the poker test to test
> pseudo random bit generators.
> Iam reading the bits from a text file (1 bit per line), which causes
> each bit to be stored in an element of a numeric vector.
>
> What Iam trying to do is to extract a "block" of bits of arbitray size
> from the original vector into a smaller numeric vector and then count
> this binary number
> (and keep repeating this until the end of the vector, so that I get a
> vector containing the number of times each binary number has occured) e.g.
>
> original vector:
> "0", "1","1","0","0","1","0","1","1"
>
> using a block size of 3 bits the first smaller vector becomes:
> "0", "1", "1"
>
> At the momemt I do this by iterating through the original vector and set
> the ith element of the smaller vector.
> I have looked at using the subset() function but it seems to operate on
> a vector's content rather than index.
>
> This causes the following two main questions:
> 1. Is there a way to specify a range of vector elements?
> 2. Is this the most efficient method, since this could be extremly time
> consuming when used to test millions of bits?
>
>
> Thanks very much in advance
>
> Otis Laws
>
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