MATLAB: How to save specific rows of a Cell Array

cell arrayssave

Hi,
I have a cell array O which stores the output of an iterative algorithm. After each 1000 iteration, I want to save the last 1000 rows of O in a .mat file and append it to the previously saved O,
O is a 20000×2 cell array. Each cell in the first column consists of a 95×4 cell which again consists of 1×5 cells. The second column is a 1×1 matrix.
In the 1000th iteration, I want to save the first 1000 rows of O in a .mat file.
In the 2000th iteration, I want to save the second 1000 rows of O (1001th row to 2000th row) and append it to the previously saved .mat file.
In the 3000th iteration, I want to save the third 1000 rows of O (2001th row to 3000th row) and append it to the same .mat file.
and so on……
I use the following code:
    if rem(it,1000) == 0
       save('O.mat',O(it-999:it), '-append');
    end
and I receive the following error:
Can someone please help me with this?
    Error using save
Must be a string scalar or character vector.
Error in HMainCode (line 90)
       save('O.mat',O(it-999:it), '-append');

Best Answer

When using save, the second input must be a variable name, not data. The variable name is text (string scalar or character vector.
Here is a description of what -append does from the save documentation page.
save(filename,variables,'-append') adds new variables to an existing file. If a variable already exists in a MAT-file, then save overwrites it with the value in the workspace.
For ASCII files, '-append' adds data to the end of the file.
Perhaps this example on the matfile documentation page is what you want?
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