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speedup cut_polygon_with_line using line_prep

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This commit is contained in:
Laura Klünder 2017-11-18 20:39:23 +01:00
parent 3245837028
commit 2d735cf7fc
1 changed files with 7 additions and 3 deletions
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10
src/c3nav/mapdata/utils/geometry.py
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@ -8,7 +8,7 @@ import matplotlib.pyplot as plt
from django.core import checks
from matplotlib.patches import PathPatch
from matplotlib.path import Path
from shapely import speedups
from shapely import prepared, speedups
from shapely.geometry import GeometryCollection, LinearRing, LineString, MultiLineString, MultiPolygon, Point, Polygon
if speedups.available:
@ -132,9 +132,10 @@ def cut_line_with_point(line: LineString, point: Point):
LineString(pointlist + line.coords[i+(1 if subdistance == distance else 0):]))
def cut_polygon_with_line(polygon: Union[Polygon, MultiPolygon], line: LineString, debug=False) -> Sequence[Polygon]:
def cut_polygon_with_line(polygon: Union[Polygon, MultiPolygon, Sequence[Polygon]], line: LineString) -> List[Polygon]:
orig_polygon = assert_multipolygon(polygon) if isinstance(polygon, (MultiPolygon, Polygon)) else polygon
polygons: List[List[LinearRing]] = []
# noinspection PyTypeChecker
for polygon in orig_polygon:
rings = getattr(polygon, 'c3nav_cache', None)
if not rings:
@ -144,8 +145,11 @@ def cut_polygon_with_line(polygon: Union[Polygon, MultiPolygon], line: LineStrin
# find intersection points between the line and polygon rings
points = deque()
line_prep = prepared.prep(line)
for i, polygon in enumerate(polygons):
for j, ring in enumerate(polygon):
if not line_prep.intersects(ring):
continue
intersection = ring.intersection(line)
for item in getattr(intersection, 'geoms', (intersection, )):
if isinstance(item, Point):
@ -275,7 +279,7 @@ def cut_polygon_with_line(polygon: Union[Polygon, MultiPolygon], line: LineStrin
new_polygon = Polygon(polygon[0], tuple(polygon[1:]))
new_polygon.c3nav_cache = polygon
result.append(new_polygon)
return tuple(result)
return list(result)
def clean_cut_polygon(polygon: Polygon) -> Polygon: