Loading a cell in Matlab - matlab

Question

I have saved a Matlab file in the computer memory called data.mat. The file is structured as a cell with dimension 13x1. To save the file, I have used the command save('data.mat', 'data').
Now, I want to load the file and transform it.
This is what I am doing at the moment
%Load data
load data
%Transform data
for n=1:13
data{n}(:,1)=rand(10,1); %replace first column
end
However, I get as a warning message on the Matlab script:
"The variable data appears to change size at every loop iteration. Consider preallocating for speed".
In short, the script does not recognise that I have loaded a cell.
How can I fix this? It is not an error message and Matlab does OK when running the code. I just want to remove the warning thing.

Answer 1

You're getting this warning because the Editor has no way of knowing what format your variable data will have until it is loaded from the MAT file. Since data isn't defined, it likely assumes you are making it from scratch and issues the warning. If you're certain you aren't going to be growing your cell array (i.e. you will only ever modify existing cells), you can just suppress the warning by adding this as the first comment on that line:
%#ok<SAGROW>
Or by right clicking on the highlighted word data and selecting the options "Suppress.. On This Line", which will add the comment for you.
More information on this can be found in the documentation.