Removing low values from a matrix

Hi

I have a small problem, I have a 134x10 matrix, which has some noise elemetns. I would like to remove them.

As in the picture below, all elements less than 0.0108 are noise. I am attaching the file

I tried this code

ModeShapes(ModeShapes < 0.01) = [];

but this doesnot works as I want.

Does anybody knows how it can be done

[Jan]

You explain, that the shown code does not work as you want, but you forgot to mention, what you want instead. What do you want to happen?

[Chris Dan]

Hi,

This is what I get, the matrix changes dimensions

[Jan]

Of course the matrix changes its dimensions, when you delete elements. This belongs to the definition of matrices: All rows and columns need to have the same number of elements, respectivly. See an example:

A = [1, 2; 3, 4]

What do you expect, if you "remove" the 1st element? The output cannot be a 2x2 matrix, if there are 3 elements only.

Yo you can set the value of an element to 0 or to NaN, but there is no way to "remove" it. You can remove rows and/or columns, but not elements.

[Chris Dan]

Okay,

and if I want to remove the rows that have neglible values, how to do that

[Jan]

Exactly as @KALYAN ACHARJYA has posted already, or slightly faster:

X(any(X < 0.0108, 1), :) = [];

Answer 1

[KALYAN ACHARJYA]

Remove menas, you have to replace by other certain values, so that it can be easily distinguishable.

mat(mat<0.0108)=0

or

mat(mat<0.0108)=NaN

More: You cann't completely delete the certain matrix elements (replace option), but you can either delete the certain rows or column easily complete.

[Chris Dan]

Hi,

yes, I want to delete those rows which are less than 0.01

[KALYAN ACHARJYA]

[r,~]=find(mat<0.0108);
mat(r,:)=[]

The code will delete the all rows, if it has any one or more element<0.0108. The resultant matrix will have reduced number of rows after deletion (if any matrix element have less than 0.0108).

[Chris Dan]

it is not working, I am getting a 0 x 10 matrix.

I am attaching the file

[KALYAN ACHARJYA]

Yes, because there are atleast one value (which is less than 0.0108) in each row of ModeShapes matrix, hence it shows the all rows deletion.

Rethink on "yes, I want to delete those rows which are less than 0.01"?