Create matrix by repeatedly overlapping a vector

Question

I\'m having great difficulty coding the following in MATLAB: Suppose you have the following vector:

a   
b
c
d
e
f
g
h
...

Specifying an (e

Answer 1

Here's a general way to do what you want:

1) Calculate the appropriate window width (and corresponding shift)
2) Determine the start indices of each column by iterating from 1 by the amount you want to shift the window each column, up to the final value. Make this a row vector.
3) Use bsxfun to expand this to a matrix of indices.
4) Use the indices to get the values from the original vector.

vec = 1:17; #% original data vector
num_windows = 3; #% specified number of windows
possible_window_length = 1:length(vec);
window_length = possible_window_length(find(possible_window_length +...
    (num_windows-1) * possible_window_length/2 < length(vec),1,'last'));
window_shift = floor(window_length)/2;
window_length = window_shift * 2; #% calculated window length
max_final_start_index = (length(vec)-window_length+1);
start_indices = 1:window_shift:max_final_start_index;
inds = bsxfun(@plus,start_indices,(0:window_length-1)');
soln = vec(inds); #% get the solution
num_excluded_vals = max_final_start_index - start_indices(end)
disp(soln);
num_excluded_vals =  1
disp(soln);
    1    5    9
    2    6   10
    3    7   11
    4    8   12
    5    9   13
    6   10   14
    7   11   15
    8   12   16