Change preprocessing parameter in neural network

Hi!

I am using neural networks to reconstruct rainfall time series. Since the network sometimes generates negative rainfall, I would like to change the scaling in the preprossesing function 'mapminmax' to [0.1 0.9] instead of the default [-1 1].

To do this, I've tried to change the ymin and ymax reachable through processParams.

% Choose Input and Output Pre/Post-Processing Functions

net.inputs{1}.processFcns = {'removeconstantrows','mapminmax'};

net.outputs{2}.processFcns = {'removeconstantrows','mapminmax'};

net.inputs{1}.processParams{2} %Returns the parameters for 'mapminmax'

net.inputs{1}.processParams{2}(1).ymin   %This returns -1

net.inputs{1}.processParams{2}(1).ymin = 0.1; %But I can't change the parameter

This code generates the following:

ans = 

      ymin: -1
      ymax: 1

ans =

      -1

??? Undefined function or variable "processParams".

Error in ==> network.subsasgn>network_subsasgn at 118
        if isempty(err), [net,err] = setInputProcessParam(net,i,processParams); end

Error in ==> network.subsasgn at 11
net = network_subsasgn(net,subscripts,v,netname);

Error in ==> NNReconstructRain at 26
net.inputs{1}.processParams{2}(1).ymin = 0.1;

How can I change the value?

Thanks

Lova

Answer 1

[Mark Hudson Beale]

You can try this workaround:

net = struct(net);
net.inputs{1}.processParams{2}.ymin = 0.1;
net = network(net);

Answer 2

[wonderboy]

i have the same problem in MATLAB r2010b. when i want to set the ymin or y max property of the mapminmax process function i get an error. see:

net.inputs{1}.processParams{3}.ymin = 0
??? Undefined function or variable "processParams".

however, on the r2010a, you won't see the above error.

i wonder sometimes, do the designing team test the product at all???!

the strange thing is that, in the HELP document, on advanced Topic/custom network, when they reach to this point, they skipped it! see (exact copy/paste from MATLAB Neural Network User Guide 7):

Set the second input vector ranges to be from -2 to 2 for five elements as follows:

net.inputs{1}.processFcns = {'removeconstantrows','mapminmax'};

View the new input properties. You will see that processParams, processSettings...

as you see on above they forgot to write this:

net.inputs{1].processFcns{2}.ymin = -2;
net.inputs{1].processFcns{2}.ymax = -2;

however, maybe they knew, this version's bug on this command!

this is really embarrassing.