Python Ctypes Examples: Difference between revisions
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See [[GRASS and Python]] for more information. See also [http://trac.osgeo.org/grass/browser/grass/trunk/doc/python/raster_example_ctypes.py raster], [http://trac.osgeo.org/grass/browser/grass/trunk/doc/python/vector_example_ctypes.py vector] sample scripts. | See [[GRASS and Python]] for more information. See also [http://trac.osgeo.org/grass/browser/grass/trunk/doc/python/raster_example_ctypes.py raster], [http://trac.osgeo.org/grass/browser/grass/trunk/doc/python/vector_example_ctypes.py vector] sample scripts. | ||
__TOC__ | |||
== Raster == | == Raster == | ||
Revision as of 19:58, 26 February 2011
See GRASS and Python for more information. See also raster, vector sample scripts.
Raster
Vector
Accessing feature geometry
This script switches X, Y coordinates and multiple them by -1.
#!/usr/bin/python
import sys
import grass.script as grass
from grass.lib.vector import *
if len(sys.argv) < 2:
sys.exit("Usage: %s: vector" % sys.argv[0])
name = sys.argv[1]
map_info = pointer(Map_info())
points = Vect_new_line_struct()
cats = Vect_new_cats_struct()
c_points = points.contents
level = Vect_open_update(map_info, name, "")
if level < 2:
sys.exit("Topology not available")
nlines = Vect_get_num_lines(map_info)
for line in range(1, nlines + 1):
ltype = Vect_read_line(map_info, points, cats, line)
if line % 100 == 0:
sys.stderr.write("\r%d" % line)
for i in range(c_points.n_points):
x = c_points.x[i]
c_points.x[i] = -1 * c_points.y[i]
c_points.y[i] = -1 * x
Vect_rewrite_line(map_info, line, ltype,
points, cats)
line += 1
sys.stderr.write("\r")
Vect_destroy_line_struct(points)
Vect_destroy_cats_struct(cats)
Vect_build_partial(map_info, GV_BUILD_NONE)
Vect_build(map_info)
Vect_close(map_info)