Asked by Ms. Mat
on 27 Dec 2012

Is it possible to find mean and std dev. of every row in a huge matrix with double data and a lot of NaN interspersed without looping through every row ?

A = [1 2 NaN; 4 NaN 6 ; 8 9 10]

output = 1.5 5 9

*No products are associated with this question.*

Answer by Matt J
on 28 Dec 2012

Edited by Matt J
on 29 Dec 2012

Accepted answer

If you have the Statistics toolbox, you can use nanmean(A,2) and nanstd(A,2).

If you don't have the toolbox, you can still avoid looping by doing

B=A; map=~isnan(A); B(~map)=0; N=sum(map,2);

rowmeans = sum(B,2)./N; rowstds = sqrt( sum(B.^2,2)./N -rowmeans.^2 );

If A is of type sparse, however, the above may need to be modified for efficiency's sake.

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

Learn moreOpportunities for recent engineering grads.

Apply Today
## 0 Comments