How can I find the maximum element of each column of a cell array

I have a cell array like this:

if true
 ca={'x' 1 1 9 3;'y' 5 1 1 1; 'z' 5 7 5 9};

end

I have to find the max number of each column then divide all element of that column to maximum I wrote this code but it had errors:

if true

for j=2:3

max_column=max(ca(:,j));

for i=1:5
ca(i,j)= ca(i,j)/max_column;
end
end
disp(ca)  
end

Please help me to edit this code. thanks in advance

Answer 1

[Gopalkrishna Bhat]

Hi Afsane,

The first column of char elements have to be removed & then the cell needs to converted to a matrix. Then you can run the code.

ba={'x' 1 1 9 3;'y' 5 1 1 1; 'z' 5 7 5 9};

temp = [ba(:,2),ba(:,3),ba(:,4),ba(:,5)];

ca = cell2mat(temp)

for j=1:4

max_column=max(ca(:,j));

for i=1:3

ca(i,j)= ca(i,j)/max_column;

end

end disp(ca)

[Guillaume]

Please use proper formatting for code. People answering question are expected to know how to use the forum tools. You can either select the code part of your post, then click on the {} Code button, or just put two spaces before each line.

Secondly, learn to use matrix operations instead of loops. Your answer can be rewritten as:

ba={'x' 1 1 9 3;'y' 5 1 1 1; 'z' 5 7 5 9};
temp = ba(:, 2:5);  %much clearer than concatenation
ca = cell2mat(temp);
max_column = max(ca); %no need for loop. max by default work on columns
ca = bsxfun(@rdivide, ca, max_column;   %division of matrix by row

[Guillaume]

Afsane's comment moved here:

Hi dear friends

thanks for your answers but at the end of my code I have to convert regular array (ca) into cell array. How can I do that?

[Guillaume]

Use num2cell to convert the matrix back to a cell array

[Afsane Afsane]

Thank you so much!!!

[Afsane Afsane]

you mean like this?

for i=1:4
  k=1;
  for j=2:3
      ba(i,j)=num2cell(ca(i,j));
      k=k+1;
  end
end

[Guillaume]

No, I mean:

 ca(:, 2:end) = num2cell(ba);

for loops are often unnecessary in matlab. You can operate on the whole matrix / cell array at once.

[Afsane Afsane]

Thanks a lot!!!

Answer 2

[Jos (10584)]

Life would be much easier if you didn't have your data arranges like this in the first place. How did you get this cell array? I strongly suggest you reconsider your approach.

[Stephen23]

Yes!

Strangely it seems to be the people with the most awkward and bizarre nested data arrangements that insist that "this is the only way" to arrange it, and that "it has to be this way..."... usually followed up with some painful loops and a whole brace [sic] of braces, parentheses and brackets...

Sigh