'apply' 'reverse' in mapminmax

Question

nguyen tien 2016-3-25

2
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/275362-apply-reverse-in-mapminmax

编辑： KAE 2018-10-9

hi everyone, what are 'apply' and 'reverse' in mapminmax function in neuron network? if i dont use them in mapminmax, why result in ouputs neuron network is different.

p = [0, 1, 2, 3, 4, 5, 6, 7, 8];

t = [0, 0.84, 0.91, 0.14, -0.77, -0.96, -0.28, 0.66, 0.99];

nneuron = 5;

net = feedforwardnet(nneuron);

net.inputs{1}.processFcns{2} = 'mapminmax';

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

net = configure(net, p, t);

net.trainParam.epochs = 50;

net.trainParam.goal = 0.01;

net = train(net, p, t);

y1 = sim(net, p)

pn = mapminmax('apply', p, net.inputs{1}.processSettings{2});

y2n = mySigmoidalNetwork(pn, net, nneuron);

y2 = mapminmax('reverse', y2n, net.outputs{2}.processSettings{2})

function out = mySigmoidalNetwork(in, net, nneuron) Nin = length(in);

IW = net.IW{1,1};

B1 = net.b{1};

b1 = B1(1);

LW = net.LW{2,1};

b2 = net.b{2};

h = tansig(IW*in+B1*ones(1,Nin));

out = LW*h + b2;

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Answer 1

KAE 2018-10-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/275362-apply-reverse-in-mapminmax#answer_340507

编辑：KAE 2018-10-9

mapminmax is a scaling that is applied to your input data to make it in the [-1,1] range, which you want to do. Then 'reverse' can undo the scaling, which is actually done automatically if you use your net to estimate results. If you don't apply the scaling on the inputs (which you should have a good reason not to do), you will get different results. There is a lot of information on scaling here .