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?

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Angelo Scacciavillani 2018-5-19

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Answer 1

Preethi Ayyamperumal 2018-5-22

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在 MATLAB Online 中打开

"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