利用MATLAB中gatool快速實現訓練神經網絡的遺傳算法程序

1、利用MATLAB中gatool快速實現訓練神經網絡的遺傳算法程序Deng Da-PengEmail: rexdengGenetic Algorithm，as an famous intelligent algorithm based on evolutionary thoughts, has been widely used to weights training and parameters optimization of neural networks. Essentially, GA is a global stochastic searching algorithm, which ap

2、proximating global minima through Selection、Crossover and Mutation operators. It is difficult for many researchers to utilize advanced programming languages to implement GA. Actually, MATLAB provide us a very good graphic user interface of GA, named gatool, in GADS toolbox.Below contents illustrate

3、how to use this GUI tool to implement combination of GA and NN. In this case, I construct a feed forward network, which topological structure is 5-3-1, transfer functions are tansig and purelin for hidden and output layer, respectively. The key step is write a function to calculate fitness of chromo

4、somes in GA population. Below code is implement this fitness calculating function in this case.function netout = netcal(pm) iN=5; hN=3;oN=1; % add your training sets here P= ; T= ; % Pre-processing data sets Pn,minP,maxP,Tn,minT,maxT = premnmx(P,T); net=newff(minmax(Pn),hN,oN,'tansig','p

5、urelin'); x,y=size(pm); for j=1:hN x2iw(j,:)=pm(1,(j-1)*iN+1):j*iN); end for k=1:oN x2lw(k,:)=pm(1,(iN*hN+1):(iN*hN+hN); end x2b=pm(1,(iN+1)*hN+1):y); x2b1=x2b(1:hN).' x2b2=x2b(hN+1:hN+oN).' net.IW1,1=x2iw; net.LW2,1=x2lw; net.b1=x2b1; net.b2=x2b2; netout=mse(sim(net,Pn)-Tn); % this erro

6、r function provides fitness for chromosomeOK, save this function with a name, i.e., netcal.m. Then, let's start gatool in MATLAB command line. The GUI of gatool is below.click then launchparameters settingclick and see helpenter num of weightsenter fitness functionFill name of fitness calculatin

7、g function in fitness function textbox, but note that add '' before function name. Calculate numbers of weights of network, in this case is 22. Then, you need set parameters of GA in right. This step need you understand GA. If any question, you can see help.Complete all these steps, click st

8、art button and launch training. When training process is end ,you will see a best chromosome in lower corner of left. This final result is best weight array of NN trained by GA. Change it to weight matrix and transfer to network according to fitness function code, then simulation with working sets a

9、nd observe network performance.You can generate a m files through "generate M-file" in "file" menu. In this case, the M-file code is showed below. You may add some code in the end of this function for convenience.OK, it is end. Thanks for your reading and hope for your reviews an

10、d comments.best chromosomefunction X,FVAL,REASON,OUTPUT,POPULATION,SCORES = untitled% This is an auto generated M file to do optimization with the Genetic Algorithm and% Direct Search Toolbox. Use GAOPTIMSET for default GA options structure. %Fitness functionfitnessFunction = netcal;%Number of Varia

11、blesnvars = 22; /CEE/professional_development_programs/ %Start with default optionsoptions = gaoptimset;%Modify some parametersoptions = gaoptimset(options,'PopInitRange' ,-0.5 ; 0.5 );options = gaoptimset(options,'StallGenLimit' ,100);options = gaoptimset(options,'CrossoverFcn' , crossoverheuristic 1.2 );options = gaoptimset(options,'MutationFcn' , mutationgaussian 1 1 );options = gaoptimset(options,'Display' ,