Is there any way to load parts of a large table from a mat-file?

I a trying to load parts of a very large table using subindexing.

f=matfile(fileName);
sub=f.X(1:10,:);

I get the following error: The variable 'X' is of class 'table'. To use 'X', load the entire variable. Why? Should I store tables in a different format than matfiles?

M

[Adam]

I've never really used tables, but from what I have seen they are easy to concatenate so you could save them in smaller chunks in the first place rather than 1 large table in a mat file.

[MSTK]

Sure, as a workaround that would do. However, the main advantage of the matfile functionality is to subindex variables that are too large to fit in memory. It seems quite strange that this is not implemented for tables.

[Adam]

There are limitations on how you can index into ordinary arrays also - e.g. you have to use contiguous indices. These limitations may cause tables to be unsupported based on how they are stored.

Answer 1

[Steven Lord]

This is one of the documented limitations of the matfile object.

" matfile does not support indexing into:

• Variables of tables"

Since you're working with data that's too big to fit in memory, you should explore if tall arrays satisfy your needs. You can create tall table arrays as shown in the "Creating Tall Tables" section of that documentation page.

[MSTK]

Ok, hopefully to be changed by Mathworks in a future release.