How to save the output of matrix calculation with different dimension

Matrix A is as follows:

A = [0.535700142949073  0.979891844387851  0.971530253658353  0.0298279396616543  0.594892834326848  0.000439003167024231  0.000514749528323066  0.946720656164921  0.625164300616741  0.134751154634228
0.00152314772823977  8.49695682929950e-05  0.000136144135877524  0.000115671549970599  0.00489725988685105  0.998565384853671  0.998310619065266  0.000278522318895896  0.000660749829483171  0.000442148312929598
0.0778175636147425  0.00460710234090386  0.00710916350708422  0.00809442181570768  0.140394113265490  0.000557855340915817  0.000658209914611258  0.0147205564442349  0.0462953048979571  0.0292516708278132
0.384959145707945  0.0154160837029518  0.0212244386986851  0.961961966972667  0.259815792520811  0.000437756638388837  0.000516421491799660  0.0382802650719480  0.327879644655819  0.835555026225029];

I need a for loop for the following calculations and save them in separate matrices (because dimension of each index is different):

maxA = max(A);
index1 = find(A(1,:) == maxA);
index2 = find(A(2,:) == maxA);
index3 = find(A(3,:) == maxA);
index4 = find(A(4,:) == maxA);

% this is my code, but seems not correct!
n = 4;
for i=1:n;
index(i) = find(A(i,:) == maxA);
end

[Stephen23]

@Mohammad Hesam: Do not create numbered variables. Although beginners think that numbered variables are a great idea it inevitably leads them to ask how to dynamically access variable names. Bad idea! Just consider this: numbered variables are de facto indices, so therefor just turn them them into real indices, exactly like Guillaume has said several times already. Use a cell array (or numeric array if possible), exactly like Guillaume explained. This is a much faster and much more robust way to program.

Here is a long explanation of why accessing dynamic variables names is a really bad way to program:

http://www.mathworks.com/matlabcentral/answers/196952-how-to-create-new-variables-in-batches-with-strcat

Answer 1

[Roger Stafford]

Based on the fact that you appear to be seeking four index values, I am guessing that what you actually want are the maximum values occurring in each of the four rows and their corresponding column indices. If so, this is what you should write:

[maxA,Index] = max(A,[],2);

The array 'maxA' will then be a four-element column vector containing the maximum values for each of the four rows. The array 'Index' will be a four-element column vector containing the (presumably) desired corresponding four column indices for these four maximums.

Read the description of 'max' in:

   http://www.mathworks.com/help/matlab/ref/max.html

Answer 2

[Guillaume]

You do not want to save the result as separate numbered variables. As a rule, if you start numbering variables, you're doing it wrong.

In your case, you want to save your result as a cell array of vectors. The fix is easy just replace index(i) by index{i}, so:

for i=1:size(A, 1) %do not use hardcoded constants
  index{i} = find(A(i,:) == maxA); 
end

Another way to obtain the same result:

index = cellfun(@(row) find(row == maxA), num2cell(A, 2), 'UniformOutput', false);

[Moe]

Thanks Guillaume,

If the output of the index represents row numbers in matrix D, then how can I have a set of output matrices? For example, the output of the above code is as follows:

index = [1,2,3,5,8,9]  [6,7]  []  [4,10]

and matrix T (the mother matrix) is as follows:

T = [4,5,1,7,8,2;7,5,3,2,8,2;4,5,8,7,9,1;4,5,3,6,8,7;4,5,5,8,9,1;3,1,2,9,2,2;1,1,1,4,8,8;4,5,9,2,8,2;1,5,2,6,8,5;4,5,5,5,5,2];

So, I want set of matrix D as follows:

D1 = [4,5,1,7,8,2;7,5,3,2,8,2;4,5,8,7,9,1;4,5,5,8,9,1;4,5,9,2,8,2;1,5,2,6,8,5];

D2 = [3,1,2,9,2,2;1,1,1,4,8,8];

D4 = [4,5,3,6,8,7;4,5,5,5,5,2]

[Guillaume]

Once you have the index cell array, it's very easy to obtain a D cell array with:

D = cellfun(@(rows) T(rows, :), index, 'UniformOutput', false);

Or using a loop:

for i = 1:numel(index)
   D{i} = T(index{i}, :);
end

You could merge the two loops into one as well.

[Moe]

Thanks Guillaume, I want to have seperate matrix for each cell in D. I used the following code:

D_set = cell2mat(D)

But, it stored all cell in one matrix, how can I have

D1 = 
D2 =
D3 = 
D4 = 
.
.
.

[Guillaume]

I'll repeat what I said: "You do not want to save the result as separate numbered variables. As a rule, if you start numbering variables, you're doing it wrong."

Leave it as a cell array. It's no more difficult to address it as :

D{1} = 
D{2} = 
D{3} = 
...