On 12/11/14 05:10, Thomas Adams wrote:
I need to generate an ascii text file from a flow direction grid that
consists of (among a couple other things that don't really matter at
this point) for each pixel:
Rainer has already given you a whole program, but here's a decomposition
in simple (untested) r.mapcalc steps:
(1) a unique integer identifier (1 -- N) for the pixel
r.mapcalc "id = row()*N + col()" # where N = nb cols * 10
(you might have to watch out for integer overflow, though)
(2) the integer identifier of the downstream pixel (assuming there is
ONLY one)
Calculate flow direction in SFD mode and use something like this:
r.mapcalc down_id = if(dir=1, id[1,1], if(dir=2, id[0,1], if(dir=3,
id[-1,1] .... etc
(3) the x,y location of the pixel (presumably, the lower left corner of
the pixel)
center of pixel:
r.mapcalc x = x()
r.mapcalc y = y()
if you want the lower left corner:
r.mapcalc x = x() - ewres()/2
r.mapcalc y = y() - nsres()/2
Then export everything with
r.stats -1 in=id,x,y,down_id
Moritz
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