Regression function of Neural Networks

Question

b 2012-5-11

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/38068-regression-function-of-neural-networks

I wrote a code for neural network for my project but, i could not find the regression function as a result. My code is;

inputs = initial1';
targets = output';
hiddenLayerSize = 6;
net = fitnet(hiddenLayerSize);
net.inputs{1}.processFcns = {'removeconstantrows','mapminmax'};
net.outputs{2}.processFcns = {'removeconstantrows','mapminmax'};
net.divideFcn = 'dividerand';  
net.divideMode = 'sample'; 
samplenet.divideParam.trainRatio = 80/100;
net.divideParam.valRatio = 15/100;
net.divideParam.testRatio = 5/100;
net.trainFcn = 'trainbr';  % Bayesian regularization
net.performFcn = 'mse';  % Mean squared error
net.plotFcns = {'plotperform','plottrainstate','ploterrhist', ...
  'plotregression', 'plotfit'};
[net,tr] = train(net,inputs,targets);
outputs = net(inputs);
errors = gsubtract(targets,outputs);
performance = perform(net,targets,outputs)

My network is running without an error. but Could not find the regression of the variables.

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Greg Heath 2012-5-13

I still do not know what you mean.

Are you looking for the mathematical equation that produces the same output as the net?

Greg

b 2012-5-14

Actually, yes.

I need the mathematical equation of regression.

How can i find that?

Thanks

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Answer 1

Greg Heath 2012-5-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/38068-regression-function-of-neural-networks#answer_47843

In general, there is no way to get "the function for each variable".

If you vary one variable with all of the other variables fixed, the result depends on the particular combination of the fixed values.

There are N combinations of I-dimensional input data. If you take each input vector, hold I-1 variables fixed and vary the remaining one over it's range, you would get N different functions for that single variable. Plotting those N functions on one plot would probably not yield enough visual information to make it worthwhile. Doing this for each variable would probably not be very enlightning.

However, there are ways to estimate the relative importance of each variable. For example, you can scramble the N values of a single variable and record the resulting error. Repeat this a number (10?,20?,30?) of times and record the summary statistics (e.g., min/median/mean/std/max) of the MSE.

The ranking of the I means and medians of the variables should yield a reasonable understanding of the importance of each variable.Hope this helps.

Greg