improve entropy

PRML · Oct 22, 2017 · c4df199 · MTobe · Jan 2, 2019 · c4df199
1 parent 159d5cd
commit c4df199
Showing 1 changed file with 2 additions and 5 deletions.
diff --git a/chapter01/entropy.m b/chapter01/entropy.m
@@ -6,10 +6,7 @@
 %   z: entropy z=H(x)
 % Written by Mo Chen ([email protected]).
 n = numel(x);
-[u,~,x] = unique(x);
-k = numel(u);
-idx = 1:n;
-Mx = sparse(idx,x,1,n,k,n);
-Px = nonzeros(mean(Mx,1));
+[~,~,x] = unique(x);
+Px = accumarray(x, 1)/n;
 Hx = -dot(Px,log2(Px));
 z = max(0,Hx);