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Vectorisation
From: |
gastonjulia |
Subject: |
Vectorisation |
Date: |
Wed, 7 Jul 2010 08:21:44 -0700 (PDT) |
Hi there,
I always knew it would come to point where my for loops are taking toooooo
long. I know that I should use vectorised code, I do.
But I can't figure out how I would vectorise this task:
- I am having a 5 times 2,000,000 matrix (approximately)
- Column 3 contains integer numbers between 1 and 20
- For each of these numbers I want to increment the corresponding field in
the `count' vector
the solution with the for loop looks something like this
octave1:>count = zeros(1,20);
octave2:>for i = 1:length(data)
octave3:> count(data(i, 3))++;
octave4:>endfor
I tried using:
octave1:>count = zeros(1,20);
octave2:>count(data(:,3))++;
which returns a vector containing all `1'
Is there a way to vectorise this task? Thanks!
Best,
Gaston
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- Vectorisation,
gastonjulia <=