Faster Matlab Table Creation

3
votes

I've noticed that creating fairly large tables in Matlab (>10,000 rows) can be quite slow because of a single function called by the constructor, checkDuplicateNames. However, I commonly am sure that the names I'm passing the table are already unique.

The following illustrates the problem well. Generating 10,000 random values takes less than a millisecond but generating a table of random values with string row names takes a second and a half with 1.4 second taken by checking for duplicate row names:

profile on; 
a = rand(10000,1);
strind = cellstr(num2str((1:10000)'));
b = table(a, 'RowNames', strind); 
profile viewer

I'm curious then, is there an alternate way to create tables in Matlab without calling the checkDuplicateNames function?

1
matlabmatlab-table
Since the table.m function is editable, why not copy its contents and create a tablewithoutchecks.m file by removing the slow lines? - Wouter Kuijsters
A bit of digging around shows that you could do this by altering the way setRowNames is called. There is a allowDups argument, that when set to 1, bypasses the check that takes up so much time. Sadly, I couldn't find how you can set allowDups = 1 at the time you call the table function, so you may still have to create some duplicate functions to get it to work. - Wouter Kuijsters
@Wouter: Because it's more than table.m (actually a whole folder of @table in the base Matlab installation) that I would have to copy, I'm doubtful that this approach would give me a table object at the end instead of a new type that doesn't work with functions written for tables. - David Kelley
@Luis: I need a way to associate the values from several series with labels, which is what tables seem to do to me. If I'd known about this a few months ago, I maybe could have worked around it but now I've got a whole project that's simply passing tables around everywhere that I'm trying to incrementally improve on. - David Kelley
@DavidKelley Can't you shadow the checkDuplicateNames function with a version of your own that does nothing? - Luis Mendo

1 Answers

1
votes

Based on this reply from a MathWorks employee, you can't do it without altering the core Matlab files.