finding the mean for large data

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FIR
FIR il 30 Nov 2012
I have 3 rows ans 192 column,i want to find mean for each 9 columns in row wise,
for ex if i have rand(3,192)
taking 3x9 , i need mean in row wise so i will have 3x1 matrix after finding mean
please help
for each 3x9 i want to perform
  2 Commenti
Jos (10584)
Jos (10584) il 30 Nov 2012
192 is not divisible by 9, so what to do with the last columns?
Image Analyst
Image Analyst il 30 Nov 2012
It's not "large" either. Before I read it I thought that he was talking hundreds of millions of elements, not five hundred and something. (And there is a "bug" for the case of calculating the mean for large numbers of singles)

Accedi per commentare.

Risposte (2)

Andrei Bobrov
Andrei Bobrov il 30 Nov 2012
Modificato: Andrei Bobrov il 30 Nov 2012
A = rand(3,192);
n = 9;
s = size(A);
out = squeeze(nanmean(reshape([A nan(s(1),mod(-s(2),n))],s(1),n,[]),2));
or
out = blockproc(A,[1 n],@(x)mean(x.data));
or
k = s(2) - rem(s(2),n);
out = [squeeze(mean( reshape(A(:,1:k),s(1),[]),2 )) , mean(A(:,k+1:end),2)];

Jan
Jan il 30 Nov 2012
A = rand(3, 192);
B = reshape(A(:, 1:189), 3, 9, []);
C = squeeze(mean(B, 2));

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