[R] vectorisation suggestion

From: Federico Calboli <f.calboli_at_imperial.ac.uk>
Date: Tue 21 Jun 2005 - 06:15:43 EST


Hi All,

I am counting the number of occurrences of the terms listed in one vector in another vector.

My code runs:

for( i in 1:length(vector3)){

   vector3[i] = sum(1*is.element(vector2, vector1[i])) }

where

vector1 = vector containing the terms whose occurrences I want to count vector2 = made up of a number of repetitions of all the elements of vector1
vector3 = a vector of NAs that is meant to get the result of the counting

My problem is that vector1 is about 60000 terms, and vector2 is 620000... can anyone suggest a faster code than the one I wrote?

Cheers,

Federico Calboli

--
Federico C. F. Calboli
Department of Epidemiology and Public Health
Imperial College, St. Mary's Campus
Norfolk Place, London W2 1PG

Tel +44 (0)20 75941602   Fax +44 (0)20 75943193

f.calboli [.a.t] imperial.ac.uk
f.calboli [.a.t] gmail.com

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Received on Tue Jun 21 06:23:25 2005

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