Replace all zeros in vector by previous non-zero value

Question

Matlab/Octave algorithm example:

 input vector: [ 1 0 2 0 7 7 7 0 5 0 0 0 9 ]
output vector: [ 1 1 2 2 7 7 7 7 5 5 5 5 9 ]

The algorithm is

Answer 1

I think is a vectorized solution. Works on your example:

V = [1 0 2 0 7 7 7 0 5 0 0 0 9]
%// This is where the numbers you will repeat lie. You have to cast to a double otherwise later when you try assign numbers to it it caps them at logical 1s
d = double(diff([0,V])>0)
%// find(diff([0,~V])==-1) - find(diff([0,~V])==1) is the length of each zero cluster
d(find(d(2:end))+1) = find(diff([0,~V])==-1) - find(diff([0,~V])==1)
%// ~~V is the same as V ~= 0
V(cumsum(~~V+d)-1)