Code Error in MATLAB

Hello All!. I need to create a matrix 81*81. I've done some coding below but it gives error (i.e. I need to get Base_Matrix, but at the end I get all the values zero). I've two matrices files i.e. A (61312*3) and B (246*1)

Total_Surveyed_Trucks=size(A,1);
Total_Survey_Number=max(B);
Base_Matrix=zeros(81,81);
for i=1:Total_Survey_Number
    Survey_Matrix=zeros(81,81);
    for j=1:Total_Surveyed_Trucks
        Origin=Survey(j,2);
        Destination=Survey(j,3);
        if Survey(j,1)==i
           if Origin~=Destination 
              Survey_Matrix(Origin,Destination);
           end
        end
    end
        Base_Matrix=Base_Matrix+Survey_Matrix;
end

Can anyone help me out? Thanks in advance.

Answer 1

[Star Strider]

I can’t run your code or simulate your data (I don’t know what it looks like), but this line:

Survey_Matrix(Origin,Destination);

is likely your problem. All it does is bring that value into the workspace. It doesn’t assign anything to it, or it to anything else.

[Star Strider]

Muhammad’s ‘answer’ moved here. It is a comment and not an answer.

------------------------------------

Thanks for your reply.

What if I do like this instead of that line:

Survey_Matrix(Origin,Destination)=Survey_Matrix(Origin,Destination)+SurveyLocation(:)

[Image Analyst]

Muhammad's reply moved here:

Thanks for your reply.

What if I do like this instead of that line:

Survey_Matrix(Origin,Destination)=Survey_Matrix(Origin,Destination)+SurveyLocation(:)

[Image Analyst]

It's easy enough to try it and see that it won't work because SurveyLocation is not defined, and even if it were it couldn't be an array since you're sticking it into an element meant for a single number.

[Star Strider]

Better, but still not a solution. The reason is that:

SurveyLocation(:)

creates a column vector out of all the elements of SurveyLocation. This will result in an error, because MATLAB cannot assign the entire vector to one scalar, that being Survey_Matrix(Origin,Destination). You have to choose one element of SurveyLocation, not the entire vector.

[Fayyaz]

I've done the below procedure but still get zero values in my base_matrix.

%%%%%%%%%%%%%%%%%%%%%%SurveyLocation%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%SurveyLocation(:,1)= Unique Survey Id 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%%%%%%%%%%%%%%%%%%%%%%Survey%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Survey(:,1)= Unique Survey Id
%Survey(:,2)= Origin Province of the Truck
%Survey(:,3)= Destination Province of the Truck
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

Total_Surveyed_Trucks=size(Survey,1);
Total_Survey_Number=max(SurveyLocation(:,1));

Base_Matrix=zeros(81,81);
for i=1:Total_Survey_Number
    Survey_Matrix=zeros(81,81);
    for j=1:Total_Surveyed_Trucks
        Origin=Survey(j,2);
        Destination=Survey(j,3);
        if Survey(j,1)==i
           if Origin~=Destination 
              Survey_Matrix(Origin,Destination)=Survey_Matrix(Origin,Destination)+SurveyLocation(i,1);
           end
        end
    end
        Base_Matrix=Base_Matrix+Survey_Matrix;
end

[Star Strider]

I suspect that the condition:

Survey(j,i) == i

is never true, so your SurveyMatrix never gets updated.

[Image Analyst]

Attach your m-file and data file(s) with the paper clip icon if you want more advice. Don't make us guess and waste our time. Make it easy for us to help you, not hard.