index to matrix columns

i want put indices to matrix columns. eg

i got 1 2 3 3 4 5 6 7 8

i want to assign indices to the column vectors [1:3:6] etc

and is there a way to put random indices? the way crossvalind command does? the problem with crossvalind is that it only accepts arrays not column vectors

any ideas?

Answer 1

[the cyclist]

I think you can do what you want using the randsample() command.

doc randsample

for details.