Please explain how this matlab code works works and what it does

Can anyone tell me how this code works?

clear

numofea=3;

subjectnum=10;

feanum=6;

featuredim=feanum*numofea;

windowsize=4;

numperfold=round(300-windowsize+1);

%datasize(subjectnum*numperfold,featuredim)=0;

alertfeasize(subjectnum*numperfold,featuredim)=0;

fatiguefeasize(subjectnum*numperfold,featuredim)=0;

subid0(subjectnum)=0;

y(subjectnum*2*numperfold)=0;

y(subjectnum*numperfold+1:end)=1;

foldidx(5*numperfold)=0;

%freqc=90;

filename={

% 'C:\Users\Adithya\Desktop\Eye tracking data\Li Rui Lin\eye_data_task_1 (5).mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Li Rui Lin\eye_data_task_4.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Yuan Liqiang\eye_data_task_1 (5).mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Yuan Liqiang\eye_data_task_4.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Adi\eye_data_task_1 (5).mat,

% 'C:\Users\Adithya\Desktop\Eye tracking data\Adi\eye_data_task_3.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Yu Lian\eye_data_task_1 (5).mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Yu Lian\eye_data_task_4.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 9\eye_data_task_1 (5).mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 9\eye_data_task_4.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 11\eye_data_task_2.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 11\eye_data_task_4.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 13\eye_data_task_3.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 13\eye_data_task_2.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 15\eye_data_task_1 (5).mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 15\eye_data_task_2.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 17\eye_data_task_1 (5).mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 17\eye_data_task_4.mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 19\eye_data_task_1 (5).mat',

% 'C:\Users\Adithya\Desktop\Eye tracking data\Subject 19\eye_data_task_2.mat'

%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

'C:\Users\Adithya\Desktop\Eye tracking data\Li Rui Lin\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Li Rui Lin\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Yuan Liqiang\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Yuan Liqiang\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Adi\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Adi\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Yu Lian\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Yu Lian\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 9\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 9\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 11\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 11\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 13\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 13\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 15\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 15\eye_data_task_4.mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 17\eye_data_task_1 (5).mat'

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 17\eye_data_task_4.mat'

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 19\eye_data_task_1 (5).mat',

'C:\Users\Adithya\Desktop\Eye tracking data\Subject 19\eye_data_task_4.mat'

};

for tt=1:subjectnum

f1=filename{2*tt-1};

f2=filename{2*tt};

load(f1)

%%%%%%%%%%%%%%%%%%%%%

if tt>0

eyeData=eyeData.data;

end

%%%%%%%%%%%%%%%%%%%%%

% %%%%%%%%%%%

%

% cleanedeye=0;

% cleanedeye(size(eyeData,1),size(eyeData,2))=0;

%

% validsizenum=1;

% for i=1:size(eyeData,1)

% cv=eyeData(i,17:18);

% dv=cv<0;

% if ~any(dv(:))

% cleanedeye(validsizenum,:)=eyeData(i,:);

% validsizenum=validsizenum+1;

% end

% end

%

% eyeData=cleanedeye(1:(validsizenum-1),:);

% %%%%%%%%%

timeidx=eyeData(:,1);

I=find(timeidx>(timeidx(end)-5*60));

sampledtime=timeidx(I);

sampledtime=sampledtime-sampledtime(1);

% eyedata0=eyeData(I,3:4); %11:12

% eyedata0(:,3:4)=eyeData(I,11:12);

eyedata0=eyeData(I,14:16); %11:12

for j=1:numperfold

tidx=find(sampledtime>(j-1) & sampledtime<(j-1+windowsize));

for k=1:numofea

eye1=eyedata0(tidx,k);

ap=statistical_fea(eye1);

alertfeasize((tt-1)*numperfold+j, ((k-1)*feanum+1):k*feanum)=ap(1:feanum);

end

subid0((tt-1)*numperfold+j)=tt;

end

load(f2)

%%%%%%%%%%%%%%%%%%%%%

if tt>0

eyeData=eyeData.data;

end

%%%%%%%%%%%%%%%%%%%%%

% %%%%%%%%%%%%

%

% cleanedeye=0;

% cleanedeye(size(eyeData,1),size(eyeData,2))=0;

%

% validsizenum=1;

% for i=1:size(eyeData,1)

% cv=eyeData(i,17:18);

% dv=cv<0;

% if ~any(dv(:))

% cleanedeye(validsizenum,:)=eyeData(i,:);

% validsizenum=validsizenum+1;

% end

% end

%

% eyeData=cleanedeye(1:(validsizenum-1),:);

%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%

timeidx=eyeData(:,1);

I=find(timeidx>(timeidx(end)-5*60));

sampledtime=timeidx(I);

sampledtime=sampledtime-sampledtime(1);

% eyedata0=eyeData(I,3:4);%11:12

% eyedata0(:,3:4)=eyeData(I,11:12);

eyedata0=eyeData(I,14:16); %11:12

for j=1:numperfold

tidx=find(sampledtime>(j-1) & sampledtime<(j-1+windowsize));

for k=1:numofea

eye1=eyedata0(tidx,k);

ap=statistical_fea(eye1);

fatiguefeasize((tt-1)*numperfold+j, ((k-1)*feanum+1):k*feanum)=ap(1:feanum);

end

end

end

featuredata=cat(1,alertfeasize,fatiguefeasize);

subid=cat(2,subid0,subid0);

featuredata(isnan(featuredata))=0;

save('C:\Users\Adithya\Desktop\Eye tracking data\Results','featuredata','subid','y')

function fea=statistical_fea(data)

N1=size(data,1);

m=mean(data);

sd=std(data,1);

difference=diff(data);

s=sum(abs(difference));

absm1=1/(N1-1)*s;

sdabsm1=absm1/sd;

for n=3:1:N1

out1(n-2,1)=data(n,1);

end

s_temp=0;

for n1=1:1:(N1-2)

temp=out1(n1)-data(n1);

s_temp=s_temp+abs(temp);

end

absm2=1/(N1-2)*s_temp;

sdabsm2=absm2/sd;

%higu=hitguchiFD(data', 32);

fea=[m,sd,absm1,sdabsm1,absm2,sdabsm2];

end

Answer 1

[Steven Lord]

I recommend contacting the person who gave you that code or the original author of the code and asking them for help understanding it. Asking focused questions about specific lines that you find particularly difficult rather than a blanket "please tell me what this does" might allow them to target their answers and so make them more useful.

Answer 2

[John D'Errico]

It can be almost impossible to figure out what undocumented code does, especially if we are not even told what it might be designed to do. This is especially true of code written by someone who is, let me say, a relative novice. We then might not even be certain if the code does what they wanted it to do in the first place.

Honestly, take poorly written, undocumented code like this, and deposit it firmly in the bit bucket. Don't trust it. If you need to do whatever that code is supposed to be doing, then you need to learn enough about the subject, as well as to learn enough about MATLAB, to write that code yourself. Then do exactly that. Then you will have code you can both trust and use, as well as modify when that proves to be necessary.

If you do desperately need to understand this code, then ask your questions of the author, who in theory can answer those questions more easily than can someone who has never seen the code, nor knows what it is supposed to do. If you do ask those questions, then make them SPECIFIC questions, much as we would need.

If you have no understanding of MATLAB at all, then explaining such a code in full depth would take us writing a complete course on both MATLAB as well as a course on the subject matter of the code.