[R] Extracting a range of elements from a vector
Otis Laws
msc22ojl at cs.bham.ac.uk
Sat Aug 25 13:43:14 CEST 2007
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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