why innerjoin does not work in parfor

Question

While writing codes with parfor in matlab. I have an error because of using innerjoin as below. I found there is a transparency error because of

N_boot = 5;
coeff_out2 = zeros(N_boot,N_coef);
sampled_id01 = zeros(Ndecisions,1);
sampled_id2 = table(sampled_id01, 'VariableNames', {'decision_id00'});
resample_dta = [];
parfor i = 1:N_boot
dta2 = dta;
dta2.Properties.VariableNames{1} = 'decision_id00';
decisions2 = unique(dta2.decision_id00);
Ndecisions2 = size(decisions2,1);
sampled_id01 = randsample(decisions2,Ndecisions2,true);
sampled_id2 = table(sampled_id01, 'VariableNames', {'decision_id00'});
resample_dta = innerjoin(sampled_id2,dta2,'Keys','decision_id00');
resample_dta = table2array(resample_dta);
result1 = mean(resample_dta(:,1:4));
coeff_out2(i,:) = result1;
end

This code keeps saying

Error using tabular/innerjoin (line 96)
Transparency violation error.

I don't know why using innerjoin as above makes the transparency error. When I use it with just for-loop, there is no problem.

Answer 1

Unfortunately, innerjoin uses the inputname function, which is causing the "transparency violation" error. There's a simple workaround, which is to wrap the call to innerjoin, like so:

innerjoinFcn = @(varargin) innerjoin(varargin{:});
parfor ...
    ...
    resample_dta = innerjoinFcn(sampled_id2,dta2,'Keys','decision_id00');
end