How can I run my code for each row of data in my excel spreadsheet?

I have a code in MATLAB which works but I want it to run individually for all the rows and produce result for each row. Instead, it runs through the data and gives result for the final row only

[Paolo]

You are probably overwriting the result of your calculations in the same variable. Initialize a cell array of size n, where n is the number of rows in your file, before your loop, and store the results of each iteration in the array.

[Ezinne Adindu]

Thanks for the reply. However, I do not know how to write the results in the preallocated cells. The written code is just basically an if else function

[dpb]

"We can't debug what we can't see..." Attach the code.

BUT, by your description you're using a loop; in Matlab you should read the data into an array and write your function to operate on the whole array; many times one avoids looping entirely and the result automagically then becomes the desired array.

BUT, "We can't debug what we can't see..." Attach the code.

[Ezinne Adindu]

H_2 = xlsread('main DGA.xlsx',1,'M2:M100');
CH_4 = xlsread('main DGA.xlsx',1,'H2:H100');
C_2H_2 = xlsread('main DGA.xlsx',1,'L2:L100');
C_2H_4 = xlsread('main DGA.xlsx',1,'J2:J100');
C_2H_6 = xlsread('main DGA.xlsx',1,'K2:K100');

R_1 = C_2H_2./C_2H_4;  
R_2 = CH_4./H_2;
R_3 = C_2H_4./C_2H_6;

if R_1<0.1
  if (R_2>=0.1 & R_2<3)
      if R_3>1
        Code=1;
       elseif (R_3>=1 & R_3<=3)
        Code=7;
      else
          Code=2;        
      end
  elseif R_2<0.1
          if R_3<1
          Code=3;
       elseif (R_3>=1 & R_3<=3)
        Code=7;
      else
          Code=10;        
          end
      elseif R_2>1
              if R_3<1
              Code=8;
       elseif (R_3>=1 & R_3<=3)
        Code=9;
      else
Code=10;        
          end
      end
elseif (R_1>=1 & R_1<=3)
  if (R_2>=0.1 & R_2<1)
      if R_3>1
        Code=2;
       elseif (R_3>=1 & R_3<=3)
        Code=5;
      else
          Code=6;        
      end
  elseif R_2<0.1
          if R_3<1
          Code=4;
       elseif (R_3>=1 & R_3<=3)
        Code=2;
      else
          Code=2;        
          end
      elseif R_2>1
              if R_3<1
              Code=2;
       elseif (R_3>=1 & R_3<=3)
        Code=2;
      else
          Code=2;  
end
      end
else
  Code=2;         
end

Answer 1

[Guillaume]

Your R_1, R_2 and R_3 are vectors. Therefore R_1 < 0.1 is a logical vectors, which you're then passing to if. It's almost always a mistake to pass a vector to if and it certainly is in your case. Despite your statement, your code, in fact, does not work. It can only work when R_1, R_2 and R_3 are scalars.

One way you could fix it is to write your if tests into a for loop that iterates over the elements of these 3 vectors simultaneously:

Code = zeros(size(R-1));
for idx = 1:numel(R_1)
  r1elem = R_1(idx);
  r2elem = R_2(idx);
  r3elem = R_3(idx);
  %now all your if, testing r1elem, r2elem, r3elem instead of R_1, R_2, R_3
  %and assigning to Code(idx) instead of Code
end

I'll point out that you also have made some mistakes in your if testing with for example

if R_3 >1    %probably should have been R_3 < 1
   ... 
elseif (R_3 >= 1 & ...)

Similarly, we find

if (R_2>=0.1 & R_2<3)
  ...
elseif R_2 > 1   %already taken care by the if for R_2 > 1 & R_2 < 3

Clearly, it is not easy to get such a spaghetti of if/else/elseif correct and thankfully there are much easier ways of obtaining the same result. E.g:

R1_thresholds = [-Inf, 0.1, 1, 3, Inf];
R2_thresholds = [-Inf, 0.1, 1, Inf];
R3_thresholds = [-Inf, 1, 3, Inf];
%create a 3D matrix that tells us which code corresponds to the intersection of each threshold
%R_1 along the rows, R_2 along the columns, R_3 along the pages
%I.E. row 1 of code_by_bin corresponds to R1<0.1, row 2 to R_1>=0.1 & R_1<1, row 3 to R_1>1 & R_1<=3, etc.
%column 1 corresponds to R2<0.1, column 2 to R2>0.1 & R2<1, etc.
%page 1 correspinds to R3<1, etc.

Code_by_bin = cat(3, ... first page for R3<1
    [3, 1, 8; ...   for R1<0.1 and R2<1, R2>=0.1 & R2<1, R2>=1 respectively
     2, 2, 2; ...   for R1>=0.1 & R1<1
     4, 2, 2; ...   for R1>= 1 & R1<3, and R2<1, R2>=0.1 & R2<1, R2>=1 respectively
     2, 2, 2], ...  for R1>=3
    [7, 7, 8;  ...  2nd page for R3>=1 & R3<3, this row for R1<0.1 and R2<1, R2>=0.1 & R2<1, R2>=1 respectively
     2, 2, 2; ...   for R1>=0.1 & R1<1
     2, 5, 2; ...   for R1>= 1 & R1<3, and R2<1, R2>=0.1 & R2<1, R2>=1 respectively
     2, 2, 2], ...  for R1>=3
    [2, 2, 2; ...   3rd page for R3>=3 everything is 2 regardless of R1 and R2
     2, 2, 2;
     2, 2, 2;
     2, 2, 2]);

%... your excel loading code

R_1 = C_2H_2./C_2H_4;  
R_2 = CH_4./H_2;
R_3 = C_2H_4./C_2H_6;
row = discretize(R1, R1_thresholds);
col = discretize(R2, R2_thresholds);
page = discretize(R3, R3_thresholds);
code = Code_by_bin(sub2ind(size(Code_by_bin), row, col, page));

I may have made some errors in the actual code values against bin because of the many mistakes in your if branches. You can fix these easily.

[Ezinne Adindu]

Wow!

Thank you so much. I implemented your first suggestion and it works

Would review the if else part of the code