# How to set values to NaN when they AREN'T within the given indices

38 views (last 30 days)
Addison Collins on 17 Jul 2021
Commented: Addison Collins on 17 Jul 2021
Hello,
I am attempting to set several values in a large matrix to NaN based on indices that I do not want to have NaN values. I attempted using logicals but matlab doesn't change anything (see photo). In this example, I expect every value but the bottom right to be set equal to NaN. I checked previous posts and this was how it was done in 2014.

Jonas on 17 Jul 2021
a=ones(3);
[X,Y]=meshgrid(1:3);
a(~(X==3 & Y==3))=NaN;
which equals
a(X~=3 | Y~=3)=NaN;
Simon Chan on 17 Jul 2021
If there is an original matrix contains different values and you want to keep part of it, you may try the following:
DataKeep = matrix_original(yind(1):yind(end),xind(1):xind(end),:); % Keep the data from the original matrix
[n,m,k] = size(matrix_original); % k should be 1000 in your case
matrix=nan(n,m,k); % Create a new matrix with NaN only
matrix(yind(1):yind(end),xind(1):xind(end),:)=DataKeep; % Put the data you want to keep in the new matrix
Addison Collins on 17 Jul 2021
@Simon ChanThat solution worked well. Sorry to both of ya for the poor explanation.

### Categories

Find more on Matrix Indexing in Help Center and File Exchange

R2020a

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!