Hello, I am trying to suppress following output 'Evaluating tall expression using the Parallel Pool 'local':' for gather function. Unfortunately it is in a parfor loop so I can't use evalc to suppress it. Can anyone help me?

Hello, I am trying to suppress following output 'Evaluating tall expression using the Parallel Pool 'local':' for gather function. Unfortunately it is in a parfor loop so I can't use evalc to suppress it. Can anyone help me?

Answer 1

[Preethi Ayyamperumal]

"evalc" violates transparency in parfor loops and hence restricted. Such transparency restrictions apply only to the direct body of the parfor construct, and not to any functions called from there.

As a workaround, hide your call to evalc('gather(argument)') in a MATLAB function and call the function from "parfor" loop to suppress the output of "gather" function.

Refer to the following code for example:

ds = datastore('airlinesmall.csv');
varnames = {'ArrDelay', 'DepDelay'};
ds.SelectedVariableNames = varnames;
ds.TreatAsMissing = 'NA';

parfor i = 1:4
    tt = tall(ds)
    a = tt.ArrDelay;
    m = mean(a,'omitnan');
    s = std(a,'omitnan');
    one_sigma_bounds = [m-s m m+s];
    supress_gather_output(one_sigma_bounds,a);   
end 

function supress_gather_output(one_sigma_bounds,a)
    [t,sig1] = evalc('gather(one_sigma_bounds)');
    [max_delay, min_delay] = evalc('gather(max(a),min(a))');
end

[Angelo Scacciavillani]

This worked well for me! Thanks a lot!