Get every 4 values of a vector and change values

Hi all,

I have a vector like this

a= [1 1 0 0 1 1 1 1 0 1 0 1 1 0 0 0 0 0 0 0 1 1 0 0]

So I would like to take every four values in a group, check if there are any ones in it, and if yes change the four values to 1. otherwise leave zeros.

So the desired vector will be:

b= [1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1]

can you help me with that?

thanks in advance,

Nikolas

Answer 1

[DGM]

Maybe something like this

a = [1 1 0 0 1 1 1 1 0 1 0 1 1 0 0 0 0 0 0 0 1 1 0 0]

a = 1×24

1 1 0 0 1 1 1 1 0 1 0 1 1 0 0 0 0 0 0 0 1 1 0 0

b = repelem(any(reshape(a,4,[]),1),4)

b = 1×24 logical array
   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1   0   0   0   0   1   1   1   1

I'm assuming the input is nominally binarized already (i.e. either logical class or numeric class but integer-valued and constrained to [0 1]). If otherwise, you'll have to explicitly convert it to logical using some desired test.

If the output needs to be numeric class, cast it using double().

[Nikolas Spiliopoulos]

thanks it works!!

Answer 2

[KSSV]

a = [1 1 0 0 1 1 1 1 0 1 0 1 1 0 0 0 0 0 0 0 1 1 0 0] ;
b = [1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1] ;
idx = bsxfun(@plus, (1 : 4), (0 : numel(a) - 4).');
a = a(idx) ;
iwant = any(a,2)' 

iwant = 1×21 logical array
   1   1   1   1   1   1   1   1   1   1   1   1   1   0   0   0   0   1   1   1   1