[R] Function to find prime numbers
tlumley at u.washington.edu
Tue Oct 13 15:41:34 CEST 2009
On Tue, 13 Oct 2009, AJ83 wrote:
> I need to create a function to find all the prime numbers in an array. Can
> anyone point me in the right direction?
It depends a bit on how big the numbers are. If the array is large but the numbers are not very large the
fastest approach is probably to create a vector of small primes and use
my_array %in% smallprimes.
For example, the first 1000 primes are at http://primes.utm.edu/lists/small/1000.txt
and the first 10000 are on the same site.
Thomas Lumley Assoc. Professor, Biostatistics
tlumley at u.washington.edu University of Washington, Seattle
More information about the R-help