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

There are many ways to do this in MATLAB by manipulating indices, procedural approaches, vectorized solutions, etc. Yet, I can't help but think of how simple some tasks might be, if MATLAB had a wee bit of support for functional style of programming. In that spirit, I present the following solution. Ensure that you don't already have any values in those variables at definition time.

take=@(mat,n)mat(1:n)
partition=@(mat,L)cell2mat(arrayfun(@(x)take(circshift(mat(:),-x*L/2),L),...
        0:fix((length(mat)-L)/2+1)-1,'UniformOutput',0))

Now try it with a test vector:

partition(1:10,4)

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

The above solution discards the final values at the end of the vector that don't fit a length L after partition. You can now build up on this to handle other arrangements and figure out optimal window lengths for minimal end wastage, etc.