Replacing values based on a condition in a matrix.

Hi there!

I have a 2by2 matrix and am trying to replace every value in the second matrix that is greater than 20 with "on".

So basically I want something like this:

1 2

2 30

30 50

40 10

55 15

to change to this:

1 closed

2 open

30 open

40 closed

55 closed

If anyone can help that would be great! Thanks!

Answer 1

[Kevin Phung]

%let M be your matrix;
ind = M(:,2) > 20; %grab indices along second column where value is > 20
M = num2cell(M); % youre going to need to turn it into a cell array
M(ind,2) = {'open'}; %set those indices to open
M(~ind,2) = {'closed'}; %set indices that are not to closed
M

let me know if this helps. Also, I suggest you read about cell arrays:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

[Megan Stapley]

Thank you so much this is exactly what I was looking for! In addition, how would I add titles to these columns?

[Walter Roberson]

M = [{'title for first column', 'title for second column'}; M];

[Kevin Phung]

Happy to help!

As for adding titles to the column, Walter's comment would work.

Another option is to turn the cell matrix into a table:

ind = M(:,2) > 20; %grab indices along second column where value is > 20
M = num2cell(M); % youre going to need to turn it into a cell array
M(ind,2) = {'open'}; %set those indices to open
M(~ind,2) = {'closed'}; %set indices that are not to closed
M = table(M(:,1),M(:,2),'VariableNames',{'Name1','Name2'})

https://www.mathworks.com/help/matlab/ref/table.html