added brandenburg example, removed unnecessary is_simple tests

examples/brandenburg.json

@@ -0,0 +1,7 @@
+{
+"type": "FeatureCollection",
+"name": "Germany_AL4",
+"features": [
+{ "type": "Feature", "properties": { "srid": "4326", "id": "62504", "name": "Brandenburg", "localname": "Brandenburg", "official_name": "", "boundary": "adminstrative", "admin_level": "4", "note": "", "wikidata": "Q1208", "wikipedia": "de:Brandenburg", "timestamp": "2018\/07\/19 01:55:20", "rpath": "62504,51477,0", "alltags": { "ref": "BB", "name": "Brandenburg", "name:am": "ብራንደንቡርግ", "name:an": "Brandemburgo", "name:ar": "براندنبورغ", "name:ay": "Brandenburg suyu", "name:az": "Brandenburq", "name:ba": "Бранденбург", "name:be": "Брандэнбург", "name:bg": "Бранденбург", "name:bn": "ব্রান্ডেনবুর্গ", "name:ca": "Brandenburg", "name:ce": "Бранденбург", "name:cs": "Braniborsko", "name:cv": "Бранденбург", "name:de": "Brandenburg", "name:el": "Βρανδεμβούργο", "name:eo": "Brandenburgio", "name:es": "Brandemburgo", "name:eu": "Brandenburgo", "name:fa": "براندنبورگ", "name:fr": "Brandebourg", "name:fy": "Brandenburch", "name:gl": "Brandeburgo", "name:gn": "Brandeburgo", "name:he": "ברנדנבורג", "name:hi": "ब्रैंडेनबर्ग", "name:hy": "Բրանդենբուրգ", "name:ia": "Brandeburgo", "name:ie": "Brandenburgia", "name:is": "Brandenborg", "name:it": "Brandeburgo", "name:ja": "ブランデンブルク州", "name:ka": "ბრანდენბურგი", "name:kk": "Бранденбург", "name:ko": "브란덴부르크 주", "name:la": "Brandenburgum", "name:lb": "Brandenburg", "name:li": "Brandeburg", "name:lt": "Brandenburgas", "name:lv": "Brandenburga", "name:mk": "Бранденбург", "name:mn": "Бранденбург", "name:mr": "ब्रांडेनबुर्ग", "name:ne": "ब्रान्डेनबर्ग", "name:nl": "Brandenburg", "name:oc": "Brandeborg", "name:os": "Бранденбург", "name:pa": "ਬ੍ਰਾਂਡਨਬੁਰਕ", "name:pl": "Brandenburgia", "name:ps": "براندنبورگ", "name:pt": "Brandemburgo", "name:ru": "Бранденбург", "name:sk": "Brandenbursko", "name:sq": "Brandenburgu", "name:sr": "Бранденбург", "name:th": "รัฐบรันเดินบวร์ค", "name:tl": "Brandeburgo", "name:uk": "Бранденбург", "name:ur": "برندنبرگ", "name:vo": "Brandänburgän", "name:yi": "בראנדנבורג", "name:zh": "勃兰登堡", "boundary": "administrative", "name:hsb": "Braniborska", "wikidata": "Q1208", "ISO3166-2": "DE-BB", "wikipedia": "de:Brandenburg", "admin_level": "4", "alt_name:cs": "Země Braniborsko", "border_type": "state", "name:prefix": "Bundesland", "de:regionalschluessel": "12", "TMC:cid_58:tabcd_1:Class": "Area", "TMC:cid_58:tabcd_1:LCLversion": "12.0", "TMC:cid_58:tabcd_1:LocationCode": "267", "de:amtlicher_gemeindeschluessel": "12" } }, "geometry": { "type": "MultiPolygon", "coordinates": [ [ [ [ 11.267612, 53.121972 ], [ 11.393711, 53.10984 ], [ 11.395417, 53.140179 ], [ 11.42153, 53.141106 ], [ 11.53464, 53.125218 ], [ 11.569435, 53.165502 ], [ 11.550948, 53.20823 ], [ 11.629009, 53.241997 ], [ 11.699607, 53.244091 ], [ 11.728497, 53.21695 ], [ 11.827851, 53.227466 ], [ 11.795949, 53.253312 ], [ 11.861657, 53.248446 ], [ 11.892566, 53.278955 ], [ 11.948175, 53.271419 ], [ 11.973662, 53.297528 ], [ 12.018622, 53.299422 ], [ 12.014026, 53.33423 ], [ 12.055753, 53.349153 ], [ 12.045029, 53.370756 ], [ 12.061792, 53.371256 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+]
+}

examples/random_points_across_italy.py

@@ -17,18 +17,6 @@
 from geovoronoi import coords_to_points, voronoi_regions_from_coords
 from geovoronoi.plotting import subplot_for_map, plot_voronoi_polys_with_points_in_area
 
-import traceback
-import warnings
-import sys
-
-def warn_with_traceback(message, category, filename, lineno, file=None, line=None):
-
-    log = file if hasattr(file,'write') else sys.stderr
-    traceback.print_stack(file=log)
-    log.write(warnings.formatwarning(message, category, filename, lineno, line))
-
-warnings.showwarning = warn_with_traceback
-
 logging.basicConfig(level=logging.INFO)
 geovoronoi_log = logging.getLogger('geovoronoi')
 geovoronoi_log.setLevel(logging.INFO)

examples/random_points_brandenburg.py

@@ -0,0 +1,85 @@
+"""
+Example script that scatters random points across Brandenburg and generates the Voronoi regions for them.
+The boundary shape of Brandenburg contains a hole (Berlin) and when loaded is regarded as "invalid" shape.
+
+Author: Markus Konrad <markus.konrad@wzb.eu>
+January 2021
+"""
+
+
+import logging
+from pprint import pprint
+
+import matplotlib.pyplot as plt
+import numpy as np
+import fiona
+import pyproj
+from shapely.geometry import shape
+from shapely.ops import transform
+
+from geovoronoi import coords_to_points, voronoi_regions_from_coords
+from geovoronoi.plotting import subplot_for_map, plot_voronoi_polys_with_points_in_area
+
+logging.basicConfig(level=logging.INFO)
+geovoronoi_log = logging.getLogger('geovoronoi')
+geovoronoi_log.setLevel(logging.INFO)
+geovoronoi_log.propagate = True
+
+#%%
+
+INPUT_FILE = 'brandenburg.json'
+N_POINTS = 20
+
+np.random.seed(20210129)
+
+print('loading %s' % INPUT_FILE)
+
+with fiona.open(INPUT_FILE) as f:
+    src_crs = pyproj.CRS.from_dict(f.meta['crs'])
+    target_crs = pyproj.CRS.from_epsg(3395)         # World Mercator CRS
+    print('source CRS:', src_crs)
+    print('target CRS:', target_crs)
+    crs_transformer = pyproj.Transformer.from_crs(src_crs, target_crs)
+    brandenburg = shape(f[0]['geometry'])
+    # note that we also apply ".buffer(0)", otherwise the shape is not valid
+    # see https://shapely.readthedocs.io/en/stable/manual.html#object.buffer on the "buffer(0)" trick
+    brandenburg = transform(crs_transformer.transform, brandenburg).buffer(0)
+
+#%%
+
+# generate some random points within the bounds
+minx, miny, maxx, maxy = brandenburg.bounds
+
+randx = np.random.uniform(minx, maxx, N_POINTS)
+randy = np.random.uniform(miny, maxy, N_POINTS)
+coords = np.vstack((randx, randy)).T
+
+# use only the points inside the geographic area
+pts = [p for p in coords_to_points(coords) if p.within(brandenburg)]  # converts to shapely Point
+del coords   # not used any more
+
+print('will use %d of %d randomly generated points that are inside geographic area' % (len(pts), N_POINTS))
+
+#%%
+
+#
+# calculate the Voronoi regions, cut them with the geographic area shape and assign the points to them
+#
+
+poly_shapes, poly_to_pt_assignments = voronoi_regions_from_coords(pts, brandenburg)
+
+print('Voronoi region to point assignments:')
+pprint(poly_to_pt_assignments)
+
+#%% plotting
+
+fig, ax = subplot_for_map()
+
+plot_voronoi_polys_with_points_in_area(ax, brandenburg, poly_shapes, pts, poly_to_pt_assignments,
+                                       point_labels=list(map(str, range(len(pts)))))
+
+ax.set_title('%d random points and their Voronoi regions in Brandenburg' % len(pts))
+
+plt.tight_layout()
+plt.savefig('random_points_brandenburg.png')
+plt.show()

geovoronoi/_voronoi.py

@@ -68,6 +68,10 @@ def voronoi_regions_from_coords(coords, geo_shape, per_geom=True, return_unassig
     if not isinstance(geo_shape, (Polygon, MultiPolygon)):
         raise ValueError('`geo_shape` must be a Polygon or MultiPolygon')
 
+    if not geo_shape.is_valid:
+        raise ValueError('`geo_shape` is not a valid shape; try applying `.buffer(b)` where `b` is zero '
+                         'or a very small number')
+
     if not per_geom or isinstance(geo_shape, Polygon):
         geoms = [geo_shape]
     else:   # Multipolygon
@@ -196,14 +200,14 @@ def region_polygons_from_voronoi(vor, geom, return_point_assignments=False):
         if not isinstance(p, Polygon):
             raise RuntimeError('generated convex hull is not a polygon')
 
-        if not p.is_valid or not p.is_simple or p.is_empty:
-            raise RuntimeError('generated polygon is not valid, not simple or empty')
+        if not p.is_valid or p.is_empty:
+            raise RuntimeError('generated polygon is not valid or is empty')
 
         if not geom.contains(p):
             p = p.intersection(geom)
 
-            if not p.is_valid or not p.is_simple or p.is_empty:
-                raise RuntimeError('generated polygon is not valid, not simple or empty after intersection with the'
+            if not p.is_valid or p.is_empty:
+                raise RuntimeError('generated polygon is not valid or is empty after intersection with the'
                                    ' surrounding geometry `geom`')
 
         covered_area += p.area
@@ -253,13 +257,19 @@ def region_polygons_from_voronoi(vor, geom, return_point_assignments=False):
 
 def get_points_to_poly_assignments(poly_to_pt_assignments):
     """
-    Reverse of poly to points assignments: Returns a list of size N, which is the number of unique points in
-    `poly_to_pt_assignments`. Each list element is an index into the list of Voronoi regions.
+    Reverse Voronoi region polygon IDs to point ID assignments by returning a dict that maps each point ID to its
+    Voronoi region polygon ID. All IDs should be integers.
+
+    :param poly_to_pt_assignments: dict mapping Voronoi region polygon IDs to list of point IDs
+    :return: dict mapping point ID to Voronoi region polygon ID
     """
 
     pt_to_poly = {}
     for poly, pts in poly_to_pt_assignments.items():
         for pt in pts:
+            if pt in pt_to_poly.keys():
+                raise ValueError('invalid assignments in `poly_to_pt_assignments`: '
+                                 'point %d is assigned to several polygons' % pt)
             pt_to_poly[pt] = poly
 
     return pt_to_poly