How do I get values of a certain parameter in a multi-dimensional matrix?

A is a variable with the size of 1000 x 500.

% Index of those that are less than 10000

Ind = A < 10000;

Why does the below give me a 500000 x 1 column data, instead of a 1000 x 500 matrix?

b = a(Ind);

What did I do wrong? How do I get the correct b with the size of 1000 x 500?

Answer 1

[Stephen23]

a(~Ind) = NaN

[Leon]

Thank you!

Answer 2

[Matt J]

b should be an Nx1 vector where N is the number of elements satisfying A<10000.

[Leon]

Thanks for the reply and sorry for my typo. So how do I get the correct b with the size of 1000 x 500?

[Matt J]

I think you need to describe better why you expect b to be a 1000x500 matrix. What if there had been only 3 elements for which A<10000?

[Leon]

If there were only 3 elements for A < 10000, the rest of them should be NaNs.

My goal is to remove missing values fillers, 9*10^26 and replace them with NaNs, so that I would have a matrix with only values that are within the normal range.

Many thanks!

[Matt J]

A(A>=10000)=nan;

[Leon]

Many thanks! That works equally well.

[Steven Lord]

You could also use standardizeMissing.

M = 9e26;
format shortg
A = [4 8 M 15 M M; 16 23 42 M M M]

A = 2×6

1.0e+00 * 4 8 9e+26 15 9e+26 9e+26 16 23 42 9e+26 9e+26 9e+26

B = standardizeMissing(A, M)

B = 2×6

4 8 NaN 15 NaN NaN 16 23 42 NaN NaN NaN