MATLAB: Replace values like (-999) in matrix to zero with one statement?!

change to zeromatrix manipulationreplacevalue

I am looking for replacing values (-999) in a matrix (m*3) to zero. I can do that using for/While loop but my program is going to be delayed to execute.

Anyone experience change a values to zero?

Thanks in advance!

Best Answer

Mohammed - try something like the following. If mtx is your matrix

 % create a 5x5 matrix
 mtx = [-999     1    2    3    4;
           5 -999     6    7    8;
           9    10 -999   11   12;
          13    14   15 -999   16;
          17    18   19   20 -999];
 % set all elements that are -999 to zero
 mtx(mtx==-999) = 0;

This works only if the value you wish to replace is an integer.

Try the above and see what happens!

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MATLAB: Eliminate rows in a matrix that have matching & different values

Assuming your matrix is A, the following code returns what you want as B.

B = sortrows(A,[1 4]);
idx = [false; diff(B(:,1)) == 0];
B(idx,:) = [];

MATLAB: How to replace numbers (-999) for NaN in a dataset

Note: datasets have been deprecated for a while. Consider using tables instead.

A dataset is a collection of variables. So you have to do your replacement per variable. e.g.

yourdataset.somevariable(yourdataset.somevariable == -999) = nan;
%same for all variables

Another option would be to use replacedata. For it to work you'll have to create an m file for a replacement function:

function X = datasetreplace(X)
   X(X == -999) = nan;
end

You can then do:

newdataset = replacedata(yourdataset, @datasetreplace)

Best Answer

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