How to add rows of data in a 5x5 Matrix

Question

Arsal15 2016-2-3

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评论： Arsal15 2016-2-3

Hi, I want to add entries in each row and put zero in the Inf place but I want to use for loop? I tried this

if true
  A = sum(A,2);
end
But I am want to put entries equal to Inf to zero and then add them.

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Answer 1

James Tursa 2016-2-3

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If you want to replace the inf values with 0 first, then

A(isinf(A)) = 0;

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Arsal15 2016-2-3

编辑：Arsal15 2016-2-3

在 MATLAB Online 中打开

Given the above matrix if I have to implement this code using for loop is it possible that I can add entries of matrix in this order.

Here tid and rid shows the entry of that column like if rid=1, tid=2 then it mean (1,2) and it will add rest of entries in the row of the above matrix i.e. (1,3)+(1,4)+(1,5).

I have written it as such but I need simple using for loop.

if true
  switch(rid)
  case 1
      if(tid ==2)
      sumA(rid,tid) = (A(1,3)+A(1,4)+A(1,5));
      end
      if(tid ==3)
      sumA(rid,tid) =(A(1,2)+A(1,4)+A(1,5));
      end
      if(tid ==4)
      sumA(rid,tid) = (A(1,2)+A(1,3)+A(1,5));
      end
      if(tid ==5)
      sumA(rid,tid) = (A(1,2)+A(1,3)+A(1,4));
      end
  case 2
      if(tid ==1)
      sumA(rid,tid)= A(2,3)+A(2,4)+A(2,5);
      end
      if(tid ==3)
      sumA(rid,tid) = A(2,1)+A(2,4)+A(2,5);
      end
      if(tid ==4)
      sumA(rid,tid) = A(2,1)+A(2,3)+A(2,5);
      end
      if(tid ==5)
      sumA(rid,tid) = A(2,1)+A(2,3)+A(2,4);
      end
  case 3
      if(tid ==1)
      sumA(rid,tid) = A(3,2)+A(3,4)+A(3,5);
      end
      if(tid ==2)
      sumA(rid,tid) = A(3,1)+A(3,4)+A(3,5);
      end
      if(tid ==4)
      sumA(rid,tid) = A(3,1)+A(3,2)+A(3,5);
      end
      if(tid ==5)
      sumA(rid,tid) = (A(3,1)+A(3,2)+A(3,4));
      end
  case 4
      if(tid ==1)
      sumA(rid,tid) = (A(4,2)+A(4,3)+A(4,5));
      end
      if(tid ==2)
      sumA(rid,tid) = (A(4,1)+A(4,3)+A(4,5));
      end
      if(tid ==3)
      sumA(rid,tid) =( A(4,1)+A(4,2)+A(4,5));
      end
      if(tid ==5)
      sumA(rid,tid) =(A(4,1)+A(4,2)+A(4,3));
      end
  case 5
      if(tid ==1)
      sumA(rid,tid) = (A(5,2)+A(5,3)+A(5,4));
      end
      if(tid ==2)
      sumA(rid,tid) = (A(5,1)+A(5,3)+A(5,4));
      end
      if(tid ==3)
      sumA(rid,tid) = (A(5,1)+A(5,2)+A(5,4));
      end
      if(tid ==4)
      sumA(rid,tid) = (A(5,1)+A(5,2)+A(5,3));
      end
end
end

Guillaume 2016-2-3

编辑：Guillaume 2016-2-3

在 MATLAB Online 中打开

Wow! You like copy pasting . As soon as you start writing lines of code that only differ according to a pattern, you have to think that the program can do that for you.

The whole of the above code could be replaced by these two lines:

rows = [1, 2, 3, 1, 1]; %row to sum
sumA(rid, tid) = sum(A(rows(rid), setdiff(1:5, [rid tid])));

And if you made a typo and forgot to replace the row number in the case 4 and case 5 (another reason for not copy-pasting redundant code), then it's even simpler:

sumA(rid, tid) = sum(A(rid, setdiff(1:5, [rid tid])));

Arsal15 2016-2-3

Thanks alot Guillaume :)

I think in the rows = [1,2,3,4,5] ?? You solved my issue and what if I have to choose a non zero entry of the matrix from a 5x5 matrix. Only one non zero and all zeros and I have to pick that and use for my calculations.

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