From 6c51a29ca219cb206107b4ed1db36e843e5100c9 Mon Sep 17 00:00:00 2001
From: neingeist <neingeist@bl0rg.net>
Date: Mon, 17 Nov 2014 23:13:57 +0100
Subject: [PATCH] Compute centroid means (vectorized)

---
 ex7/computeCentroids.m | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/ex7/computeCentroids.m b/ex7/computeCentroids.m
index 2bd6095..5cadc20 100644
--- a/ex7/computeCentroids.m
+++ b/ex7/computeCentroids.m
@@ -27,17 +27,9 @@ centroids = zeros(K, n);
 %
 
 for k = 1:K
-  count = 0;
-
-  % XXX vectorize
-  for i = 1:m
-    if idx(i) == k
-      centroids(k, :) += X(i, :);
-      count += 1;
-    end
-  end
-  if count > 0
-    centroids(k, :) /= count;
+  X_in_k = X(idx == k, :);
+  if size(X_in_k, 1) > 0
+    centroids(k, :) = sum(X_in_k)/size(X_in_k, 1);
   end
 end