How to prevent over-writing in my for loop?

My interpolation for loop keeps over-writing the last value, even though I assigned x2=zeros(N,2).

clear; clc;
  Folder = cd;
  N=100;
  x2     = zeros(N, 2);
  for k = 1:N;
    Driftt  = sprintf('Drift%d.out', k);
    Reactt  = sprintf('React%d.out', k);
    matDrift     = importdata(fullfile(Folder, Driftt));
    matReact = importdata(fullfile(Folder, Reactt));
    x1= matDrift(:,2);
    y1= -sum(matReact(:,2:11),2);
  [x3, ix] = unique(x1);
  y3       = y1(ix);

    [y2] = [500000, 5000000, 7000000, 8000000, 900000, 13000000, 14000000];
    x2 = interp1(y3, x3, y2, 'linear')
    end

Answer 1

[Matt J]

Your loop needs to provide an index into x2

x2(something)= interp1(y3, x3, y2, 'linear')

to tell it where to store things.

[Ismail Qeshta]

Thanks Matt. I provided

x2 = zeros(N, 2);

When I provide (k) after x2, it shows column with zeroes.

Would you please be able to explain more on the something or index?

[Matt J]

Well, if you don't provide an index, MATLAB assumes that you just want to replace the whole matrix with something else:

      >> x2=zeros(4,2)

    x2 =

         0     0
         0     0
         0     0
         0     0

    >> x2=1

    x2 =

         1

Conversely, if you give an index, you will place the right hand side into some designated part of the array.

    >> x2=zeros(4,2); x2(4,:)=[2,1]

    x2 =

         0     0
         0     0
         0     0
         2     1

So, your job is to specify where in x2 you want the result of interp1(y3, x3, y2, 'linear') inserted.

[Ismail Qeshta]

Yes. I got it. Thanks a lot Matt.

I basically had to modify the:

x2     = zeros(N, 7);

and specify the index for x2 as per your explanation, as follows:

x2 (k,:) = interp1(y3, x3, y2, 'linear')

Thank you again for the help.