[R-sig-Geo] SamplingStrata

[Matteo Mura]

Dear all,

I am going to quickly explain you what I am trying to achieve.

I have a grid of 4692 hexagons (see
https://www.dropbox.com/s/rkim7v21i1p0bet/grid.jpeg). Each hexagon has
its univocal id (ID_ES).

In order to carry out a sampling procedure with different sampling
rates (SR) I have to:

- SR 50% => divide the map in (4692/2=) 2346 strata composed by 2
adiacent hexagons, and get as a result a dataframe where each row
contains the ID_ES of the 2 hexagons, e.g.:

ID_ES1 | ID_ES2
2345 | 1654

(please note that the ID_ES is not spatially progressive, in the sense
that the ID_ES=1 is not adiacent to ID_ES=2).

Same thing for the others different SR:

- SR 25% => (4692/4=) 1173 strata composed by 4 adiacent hexagons, and
get as a result a dataframe where each row contains the ID_ES of the 4
hexagons

- SR 10% => 467 strata of 10 adiacent hexagons + 2 strata of the
remains 11 adiacent hexagons and get as a result a dataframe where
each row contains the ID_ES of the 10 hexagons + 2 rows with the ID_ES
of the 11 hexagons.

Same procedure for SR of 5% (222 strata of 20 hex + 12 strata of 21
hex) and 1% (39 strata of 100 hex + 8 strata of 99 hex).

Hope I have been clear.

Thanks in advance!