How to tell a loop to do an iteration when a new row is added to the matrix?

Hi all. I have the following loop:

x1=[6;6;5;10;7;6;5;3;8;8;5;8;5;4;2;7;4;5;7;1;5;4;7;4;8]; %variable 1
x2=[8;7;7;9;9;6;8;7;8;6;9;8;8;9;9;5;8;10;7;5;6;3;9;5;9]; %variable 2
x3=[3;3;1;8;7;3;6;3;9;5;5;2;7;10;4;8;8;9;3;2;7;1;6;2;5]; %variable 3
x4=[5;4;4;4;6;9;7;6;3;3;4;3;5;2;10;6;2;3;7;7;7;2;6;4;7]; %variable 4
x5=[19;9;16;4;9;17;6;16;8;13;17;5;8;16;14;15;16;11;12;17;20;15;9;12;18]; %variable 5
n=numel(x1);
c=[x1,x2,x3,x4,x5];%used for covariance matrix
k=size(c,2);nk=n-k;
n1=10

      for z=1:size(x1,1)
          c1=c(z:9+z,:);
          mean1=mean(c1,1);S_c=cov(c1);is_c=inv(S_c);diff_c=[mean1'-Goal];T2_c(z)=n1*[(diff_c'*is_c)* diff_c];
          plot(T2_c,'-o')
  line('XData', [0 25], 'YData', [16.2653 16.2653], 'LineStyle', '-', 'LineWidth', 2, 'Color','r') 

      end

I basically want the for loop to run every time a new row of data is added to the matrix c( a new value is added to x1, x2,x3,x4,x5).

Also is it possible to have matlab to pull out every 2nd and 3rd number of a matrix. for example, if [1,2,3,4,5,6,7,8,9,10]. i want to pull out 2,4,6,8 etc and 3,6,9,etc.

Thank you for your help!

Answer 1

[per isakson]

"[1,2,3,4,5,6,7,8,9,10]. [I] want to pull out 2,4,6,8 etc and 3,6,9,etc." that's easy:

    >> vec = [1,2,3,4,5,6,7,8,9,10];
    >> vec(2:2:end)
    ans =
         2     4     6     8    10
    >> vec(3:3:end)
    ans =
         3     6     9
    >>

or

    >> for jj = 2:10, vec(jj:jj:end), end
    ans =
         2     4     6     8    10
    ans =
         3     6     9
    ans =
         4     8
    etc.
    >>

if 10 shall not be included replace &nbsp :end &nbsp by &nbsp :end-1

&nbsp

"run every time a new row of data is added to the matrix" &nbsp Yes, it's possible. One way is to use

• OOP and
• the property attribute, SetObservable &nbsp If true, and it is a handle class property, then you can create listeners for access to this property. The listeners are called whenever property values are modified. See Property-Set and Query Events

[Nancy]

Thank you so much! I have a quick question if i want to get the first number of every three for example : vec(1:3:end) is there any way i can write it to have 10 be returned also? I want to be able to pull out the x's for example for this:

[x # # x # # x # # x # # x # # etc...]

[per isakson]

I'm missing something

    >> vec(1:3:end)
    ans =
         1     4     7    10

already returns 10. To make sure 10, the last element, is always included

    for jj = 1 : 10    
        vec( unique( [ 1:jj:length(vec), length(vec)] ) )
    end

which returns

    ans =
         1     2     3     4     5     6     7     8     9    10
    ans =
         1     3     5     7     9    10
    ans =
         1     4     7    10
    ans =
         1     5     9    10
    etc.

unique ensures that a single 10 is returned. Here is a bit of smell of Matlab. Better

    for jj = 1 : 10    
        out = vec( 1:jj:length(vec) );
        if out(end)~=10
            out(end+1) = 10;
        end 
        disp( out )
    end

next step is to replace the magic number 10 by a variable with a good name.

[Nancy]

it works! thank you so much!