Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

finding the mean for large data

Asked by FIR on 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 Comments

Jos (10584) on 30 Nov 2012

192 is not divisible by 9, so what to do with the last columns?

Image Analyst on 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)

FIR

Tags

Products

No products are associated with this question.

2 Answers

Answer by Andrei Bobrov on 30 Nov 2012
Edited by Andrei Bobrov on 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)];

0 Comments

Andrei Bobrov
Answer by Jan Simon on 30 Nov 2012
A = rand(3, 192);
B = reshape(A(:, 1:189), 3, 9, []);
C = squeeze(mean(B, 2));

0 Comments

Jan Simon

Contact us