Replace elements from a matrix with NaN and add new columns

Hello people, I have a MATLAB question about replacing certain elements in a matrix with NaN values and adding some new columns to the Matrix. I have a 64504x181 matrix. Not all columns have the same length, for shorter columns, NaN values are added till the end. Now I would like to remove certain elements from each column. I have identified the start and end indices of the elements I would like to remove. E.g. in the first column I would like to replace elements from 608 to 12128 with NaN and take all the elements from 12129 till the end into column 2 (and so, column 2 would become column 3). This is the piece of code I have so far, I am not sure how to go on from there.

ExcludePeriods is 12x2 matrix, column 1 is starting time and column 2 is end time of the data I want to exclude.

data is the matrix I want to modify, and Times is a matrix with the same size, that contains the time of each entry in data.

for i=1:size(ExcludePeriods,1)
    [ExcludeIndST(1,1),ExcludeIndST(1,2)] = find(Times == ExcludePeriods(i,1));
    [ExcludeIndET(1,1),ExcludeIndET(1,2)] = find(Times == ExcludePeriods(i,2));

      if ExcludeIndST(1,2) == ExcludeIndET(1,2)
          data((ExcludeIndST(1,1):ExcludeIndET(1,1)),ExcludeIndST(1,2)) = NaN;
      else
          data((ExcludeIndST(1,1):End),ExcludeIndST(1,2)) = NaN;
          data((1:ExcludeIndET(1,1)),ExcludeIndET(1,2)) = NaN;
      end
 end

Thank you in advance!

[JohnGalt]

As a rule, it's generally a bad idea to add columns without pre-allocating space... that is - it's better to start out by making a matrix the right size and then updating the elements with the desired values.

also - if you make a more basic example with some actual numbers it would be easier to help...

Additionally, you can uses 'logical indexing' to simplify your code... e.g.

a = 1:10
a(a>5 & a< 9)=nan % set values greater then 5 and less than 9 to nan

and doing something similar to a matrix:

   i = 1;
   a = magic(5)
   a(a(:,i)>5 & a(:,i)<12,i)=nan

[Ghazi Eltiti]

@JohnGalt Thanks for your comment. However, I find logical indexing to make the code longer and more confusing in this case. This code is working and its result is a matrix that has NaNs within the data. Now I would like move the data after the NaNs to the next column, moving all the other columns by 1 step, any idea on how I can achieve that?

[Image Analyst]

Attach your matrix in a .mat file, and then people might start working on code to help you.

[Ghazi Eltiti]

@Image Analyst Thanks for the advice, I have done that now.