def test_polygon(self):
polygon = Polygon([(0, 0), (0, 1), (1, 0)])
polygon_reversed = Polygon(
polygon.exterior.coords[::-1]
)
assert (orient(polygon, 1)) == polygon_reversed
assert (orient(polygon, -1)) == polygon
def test_geometrycollection(self):
polygon = Polygon([(0, 0), (0, 1), (1, 0)])
polygon_reversed = Polygon(
polygon.exterior.coords[::-1]
)
collection = GeometryCollection([polygon])
assert orient(collection, 1) == GeometryCollection(
[polygon_reversed]
)
assert orient(collection, -1) == GeometryCollection(
[polygon]
)
def orient(geom, sign=1.0):
if isinstance(geom, BaseMultipartGeometry):
return geom.__class__(
list(map(lambda geom: orient(geom, sign), geom.geoms)))
if isinstance(geom, (Polygon, )):
return orient_(geom, sign)
return geom
def winding_order(geom, order="CW_CCW"):
"""
Function that force a certain winding order on the resulting output geometries. One
can choose between `CCW_CW` and `CW_CCW`.
`CW_CCW` implies clockwise for exterior polygons and counterclockwise for interior
polygons (aka the geographical right-hand-rule where the right hand is in the area
of interest as you walk the line).
`CCW_CW` implies counterclockwise for exterior polygons and clockwise for interior
polygons (aka the mathematical right-hand-rule where the right hand curls around
the polygon's exterior with your thumb pointing "up" (toward space), signing a
positive area for the polygon in the signed area sense).
TopoJSON, and so this package, defaults to `CW_CCW`, but depending on the
application you might decide differently.
* https://bl.ocks.org/mbostock/a7bdfeb041e850799a8d3dce4d8c50c8
Only applies to Polygons and MultiPolygons.
Parameters
----------
geom : geometry or shapely.geometry.GeometryCollection
Geometry objects where the winding order will be forced upon.
order : str, optional
Choose `CW_CCW` for clockwise for exterior- and counterclockwise for
interior polygons or `CCW_CW` for counterclockwise for exterior- and clockwise
for interior polygons, by default `CW_CCW`.
Returns
-------
geometry or shapely.geometry.GeometryCollection
Geometry objects where the chosen winding order is forced upon.
"""
# CW_CWW will orient the outer polygon clockwise and the inner polygon counter-
# clockwise to conform TopoJSON standard
if order == "CW_CCW":
geom = orient(geom, sign=-1.0)
elif order == "CCW_CW":
geom = orient(geom, sign=1.0)
else:
raise NameError("parameter {} was not recognized".format(order))
return geom
def test_multipolygon(self):
polygon1 = Polygon([(0, 0), (0, 1), (1, 0)])
polygon2 = Polygon([(1, 0), (2, 0), (2, 1)])
polygon1_reversed = Polygon(
polygon1.exterior.coords[::-1]
)
polygon2_reversed = Polygon(
polygon2.exterior.coords[::-1]
)
multipolygon = MultiPolygon([polygon1, polygon2])
assert not polygon1.exterior.is_ccw
assert polygon2.exterior.is_ccw
assert orient(multipolygon, 1) == MultiPolygon(
[polygon1_reversed, polygon2]
)
assert orient(multipolygon, -1) == MultiPolygon(
[polygon1, polygon2_reversed]
)
def as_geojson(self, hold_crs=False):
""" Return Feature as GeoJSON formatted dict
Args:
hold_crs (bool): serialize with current projection, that could be not ESPG:4326 (which is standards violation)
Returns:
GeoJSON formatted dict
"""
if self.crs != CRS_LATLON and not hold_crs:
f = self.reproject(CRS_LATLON)
else:
f = self
shape = f.shape
if shape.is_empty:
# Empty geometries are not allowed in FeatureCollections,
# but here it may occur due to reprojection which can eliminate small geiometries
# This case is processed separately as orient(POLYGON_EMPTY) raises an exception
# TODO: do not return anything on empty polygon and ignore such features in FeatureCollection.geojson
shape = Polygon()
else:
try:
shape = orient(shape)
except Exception as e:
# Orientation is really not a crucial step, it follows the geojson standard,
# but not oriented polygons can be read by any instrument. So, ni case of any troubles with orientation
# we just fall back to not-oriented version of the same geometry
warnings.warn(
f'Polygon orientation failed: {str(e)}. Returning initial shape instead',
RuntimeWarning)
shape = f.shape
f = Feature(shape, properties=f.properties)
data = {
'type': 'Feature',
'geometry': f.geometry,
'properties': f.properties
}
return data
def test_linearring(self):
linearring = LinearRing([(0, 0), (0, 1), (1, 0)])
assert orient(linearring, 1) == linearring
assert orient(linearring, -1) == linearring
def test_multilinestring(self):
multilinestring = MultiLineString(
[[(0, 0), (1, 1)], [(1, 0), (0, 1)]]
)
assert orient(multilinestring, 1) == multilinestring
assert orient(multilinestring, -1) == multilinestring
def test_linestring(self):
linestring = LineString(((0, 0), (1, 1)))
assert orient(linestring, 1) == linestring
assert orient(linestring, -1) == linestring
def test_multipoint(self):
multipoint = MultiPoint([(0, 0), (1, 1)])
assert orient(multipoint, 1) == multipoint
assert orient(multipoint, -1) == multipoint
def test_point(self):
point = Point(0, 0)
assert orient(point, 1) == point
assert orient(point, -1) == point
