How can i extract Index values of different cell arrays

I want to extract the cell arrays w.r.to the index num,

for w =1:length(mydata)
    %[~,I]= find(mydata{w, 2}(:,2)) = find(mydata{w, 1}(:,1));
    for o = 1:length(mydata{w,2})
        index = find(mydata{w, 2}(:,2) == mydata{w, 1}(:,1)== o);
        mydata{w,3} = index;
    end
end

I have a cell which contains max and its index values in each row. Now i want to find max index values in another cell and extract those values( matrix 1*2, here i want to extract only 1st col value only). for ex. [M,I] = [2,295]. 295 index value of its max value in certain row, let say (6,26321) is the extracted index value in another cell. extract value is 6(1st col) similarly all other row cells matrix. Thanks in advance.

[jonas]

I am staring at your data but still cannot understand your explanation.

It seems you have pairs consisting of one 999x2 matrix and one 1x2 matrix, respectively. You want to extract the second column of the latter, which is an index, and do what with it?

[per isakson]

Why the Products

MATLAB Coder, MATLAB C/C++ Math Library

[Image Analyst]

Please give a larger example, with, say, a cell array of 3 rows and 2 columns for input, and the desired array or cell array for output. This is all I've got so far:

s = load('mydata21.mat')
ca = s.mydata21; % Extract cell array
celldisp(ca)
[rows, columns] = size(ca)
% Loop over every row in the cell array,
% getting the matrix, it's max, and it's index.
for row = 1 : rows
  thisMatrix = ca{row, 1};
  maxValue = ca{row, 2}(1);
  maxIndex = ca{row, 2}(2);
  fprintf('For row %d, the Max Value = %.6f, and occurs at index %d.\n',...
    row, maxValue, maxIndex);
end

I can't go further because I don't know what the "other cell" or "other row cells matrix" is.

[Ram]

@jonas thanks for your reply. From 1*2 matrix i have max and index values. for example(from data),(0.3076,690) is our max and index values. Now i want to extract the values from 999*2 matrix. where index is 690 ie.,(8.1510,110.9065). but here i want to extract first col only for each cell array matrix. i have same data for min and index values. later i want to find distance between them.

[Ram]

@image analyst thanks for your support. above code writtens only my max and index values again, But this is not my required output. here input matrix is 1*2 which has [max ind] values. but we consider only index values in order to find index values in 999*2 matrix. as i said in above. And here other cell/rows cells means to find all index values for each cell (999*2) array from the 1*2 matrix. sorry for inconvienence about explanation.

Answer 1

[jonas]

Something like this should work.

s = load('mydata21.mat')
s=s.mydata21;
c=s(:,2) %arrays with indices
d=s(:,1) %arrays with values
out=cellfun(@(x,y)y(x(2),1),c,d)

[Ram]

@jonas, wow, its worked, thanks alot. Is there any other way to do with for loop without providing vaiable name as s to the mat file. can i do it from above mentioned code. so that i can keep my code in same file.

[Stephen23]

@Ram: loading into an output variable is recommended, as it avoids several potential bugs, is more efficient, and makes debugging easier. You should load into an output argument, just as Jonas showed.

[jonas]

@Ram: No problem, I don't understand your follow-up question though. You can name the variable anything you'd like. I just stole the first line from IA's code, that's why its called s.

[Ram]

@jonas, 1. i am trying to write with for loop without using any inbuilt functions. its continuation of my entire code. 2. And, my data is already in workspace, loading again is a little bit confusion(if i create in new file, then its fine). 3. here we are finding only 1st col value. If i want to find two col values how can i do that!

[jonas]

1. Cellfun is just a clean way of performing operation on multiple cells. In this case you can do the same with a simple loop:

%%Load data
s = load('mydata21.mat')
s=s.mydata21;

%%Preallocate
out=nan(length(s))

%%Loop over each row
for i=1:length(s)
out(i)=s{i,1}(s{i,2}(2));
end

2. If your data is already loaded, just delete the first line and replace the variable with whatever you call it? I suppose you should replace s by mydata?

3. In the cellfun or the loop, just change the column index from 1 to 2.

[Ram]

@jonas Thanks alot. You are just genius and saved my time.