Append rows to .mat file

How do I append row(s) of data to an existing array in a .mat file. The following works except the 2nd to last line:

tableIt = [1 2 3;4 5 6;7 8 9];
tableMore = [10 11 12];
filename = 'aTable.mat';
data2store = 'tableIt';
more2store = 'tableMore';
save(filename,data2store');
whos('-file',filename);


m = matfile(filename,'Writable',true);
m.tableIt(end+1,:) = more2store;

whos('-file',filename);

[Walter Roberson]

save(filename, data2store, '-v7.3');

without the -v7.3, the .mat file would typically default to -v7 and those are not writable.

[Brent]

-7.3 doesn't solve the error message the code above generates:

Error using ScratchPad (line 12)

The size of the right hand side did not match the size of the indexing on the left hand side.

[Walter Roberson]

It is recommended to not use end in this context. See https://www.mathworks.com/help/matlab/ref/matlab.io.matfile.html

[Brent]

I'm looking for something that does work, do you know an alternative that works?

Answer 1

[Walter Roberson]

more2store = 'tableMore';

That is a 1 x 9 character vector.

tableIt = [1 2 3;4 5 6;7 8 9];

That is a 3 x 3 double.

m.tableIt(end+1,:) = more2store;

That attempts to store the 1 x 9 character vector into 3 columns of a double. That does not fit.

[Brent]

tableIt is a 3x3 double. I'm then trying to add another row which is a 1x3 double.

[Walter Roberson]

No, you are attempting to store the character vector 'tableMore' rather than the contents of the variable tableMore

[Walter Roberson]

If you had done

more2store = tableMore;

then it would have worked.

[Walter Roberson]

http://www.cs.utoronto.ca/~chechik/courses/csc324/white.html