Removing some indexes of a matrix in MATLAB

Question

I have a 2D matrix, A, each row representing a sample of signal,

I want to filter it by removing the samples having mean more and less than a threshold.

so I calculate the mean like m = mean(A');

then I want to do something like

A(m > 2 || m < 1 , :) = [];

Which faces with an error,

I tried doing like,

A(m > 2 , :) = [];
A(m < 1 , :) = [];

But I realized that after executing the first line, the indexes change and ...

So what can I do?

You should take a look at [this question](http://stackoverflow.com/questions/14183385/whats-the-difference-between-and-in-matlab) regarding _the difference between `|` and `||`_. (tl;dr: | can operate on arrays but || can only operate on scalars). On a side note: in order to combat the index change after `A(m > 2 , :) = [];`, you can just run `m = mean(A');` again to recalculate the indices. — Dev-iL, Oct 19 '14 at 11:38

score 1 · Accepted Answer · answered Oct 19 '14 at 21:52

The comments are suggesting you use element-wise or instead of scalar.

This:

A(m > 2 | m < 1 , :) = [];

Not this:

A(m > 2 || m < 1 , :) = [];

But, as with your other question, I strongly recommend using a dimension argument to mean instead of transposing the input matrix to mean:

m = mean(A,2).'; % NOT m = mean(A');

score 0 · Answer 2 · answered Oct 19 '14 at 07:12

0

I did this:

 A(m > 2,:) = NaN;
 A(m < 1,:) = NaN;
 A(any(isnan(A),2),:) = [];

I don't know if it is efficient enough, but it did the job.

answered Oct 19 '14 at 07:12

Rashid

2 Answers2