peter.lo...@gmx.de wrote:
> Q:The (geographic) coordinates for each raster cell should be accessible via
> coo_col = G_col_to_easting((thecolumn + 0.5), "REGION")
> coo_row = G_row_to_northing((therow + 0.5), "REGION")
>
> => how is "REGION"-related information 1) derived and 2) referred to on this
> level ?
The second argument to G_col_to_easting() and G_row_to_northing() is a
"const struct Cell_head *". The information can be obtained from
G_get_window(), e.g.:
import sys
import grass.lib.gis as gis
from ctypes import *
gis.G_gisinit(sys.argv[0])
region = gis.Cell_head()
G_get_window(byref(region))
coo_col = gis.G_col_to_easting((thecolumn + 0.5), byref(region))
coo_row = gis.G_row_to_northing((therow + 0.5), byref(region))
The ctypes interfaces are thin wrappers around the corresponding C
functions. Any script which uses them should have essentially the same
structure as a module written in C. Structures can be allocated by
using the structure name as a function, and passed by reference using
ctypes' byref() function.
--
Glynn Clements <gl...@gclements.plus.com>
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