access the respective values of matrix using the cell array cell position value

i have a matrix as shown in figure, with positions marked

I have a cell array with values

{ [ 1 4 ] ; [ 2 3] };

Now i want to take the values from position

{ [0-1 1-4] ; [0-2 2-3] } of the matrix

i.e. { [ 33 45]; [34 30] }

and get the sum of

33 + 45 +34 +30 = 142

how can i access the respective values of matrix using the cell array cell position values?

Answer 1

[Sriram Tadavarty]

Hi Elysi,

Here is what you have asked for

% Given matrix
a = [0 33 34 16 25;...
    22 0 20 12 45;...
    20 40 0 30 12;...
    16 12 30 0 44;...
    34 56 26 15 0];

% Cell positions
cellValue = {[1, 4], [2 3]};

% To make it generic, for any number of cell elements with varying size, you can use a for loop
s=0;
for i = 1:numel(cellValue)
    cellInd = cellValue{i};
    tmp = [];
    tmp(1) = a(0+1,cellInd(1)+1);
    for j = 2:length(cellInd)
        tmp = [tmp a(cellInd(j-1)+1,cellInd(j)+1)];
    end
    s = sum(tmp) + s;
end

Hope this helps.

Regards,

Sriram

[Elysi Cochin]

sir why output not coming correct for this example, the sum should be 241, when doing manually, but using the code i get 180 only

cellValue  = { [1 4 2]  [3 1 4]  [2 3] };

[  0-1     1-4     4-2
   0-3     3-1     1-4
   0-2     2-3]

33 45 26
16 12 45
34 30

Total sum = 241

[Sriram Tadavarty]

Ok sure. I wasn't aware from the problem that the cell array can vary its dimensions.

So, here is the modified code for it

s=0;
for i = 1:numel(cellValue)
    cellInd = cellValue{i};
    tmp = [];
    tmp(1) = a(0+1,cellInd(1)+1);
    for j = 2:length(cellInd)
        tmp = [tmp a(cellInd(j-1)+1,cellInd(j)+1)];
    end
    s = sum(tmp) + s;
end

Hope this helps

[Elysi Cochin]

sir answer is coming 251

but answer is 241

[Sriram Tadavarty]

Ya. Please take the latest code in the answer. I had written one value wrong in the matrix and that 10 increase is due to it. If you see the first row and third column of matrix a, it is written as 26 instead of 16.I did correct in it in the answer, take the latest code and check.

[Elysi Cochin]

Thank you sir, got it