st: xttrans frequency sampling

[Argyn Kuketayev <akuketayev@mail.primaticsfinancial.com>]

Hello

I have the dataset:

===
item, month, state
1,1,0
1,2,0
1,3,1
2,1,0
2,1,1
...
===

I declare the
xtset item month

then run
xttrans state

This runs fine for the delta=1. How can I make it ruin for delta=12 or 3?

I can do this:
keep if mod(month,12)==0

However this would run the xttrans on 1/12 of my sample. I'd like to
see the transitions between months 1 and 13, 2 and 14 all together
etc.

cheers
-- 
Argyn Kuketayev
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