MATLAB: Creating a Matrix with for loop

Question

I have a fairly large vector named blender (45,000+). I have extracted n elements for which blender is greater than b (irrelevant). Now my difficulty is the following:

I am trying to create a 21 x n matrix with each extracted element of blender plus 10 things before, and the 10 things after, hence the reason why each column is 21.

I have been trying variations of the following:

   element=find(blender >= 120);
   NewMatrix = zeros(21, length(element));
   for i = 1:length(element)
       k = element(i);
       NewMatrix(:,i)= Matrix(blender(k-10:k+10));
   end

then I want to plot one column of the matrix at the time when I hit Enter. This second part I can figure out later, but I would appreciate some help making the Matrix

Thanks

Answer 1

If I understand well and if you want to keep it simple with an explicit for loop, what you want to do is something like that I guess:

 element=find(blender >= 120);
 NewMatrix = zeros(21, length(element));
 for ii = 1:length(element)
    k = element(ii);
    r = max(1, k-10) : min(length(blender), k+10) ; % Range of indices +/- 10
                                                    % limited to valid ids.
    NewMatrix(1:length(r),ii) = blender(r);         % Store blender on the
                                                    % valid range; next 
                                                    % elements left to 0.
 end

Cheers,

Cedric