165 lines
5.2 KiB
Python
165 lines
5.2 KiB
Python
import geohash
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import os
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import math
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import operator
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import six
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import ujson as json
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from collections import defaultdict, OrderedDict
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from leveldb import LevelDB
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from geodata.distance.haversine import haversine_distance
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class PointIndex(object):
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include_only_properties = None
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persistent_index = False
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cache_size = 0
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POINTS_DB_DIR = 'points'
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GEOHASH_PRECISION = 7
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PROPS_FILENAME = 'properties.json'
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POINTS_FILENAME = 'points.json'
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INDEX_FILENAME = 'index.json'
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def __init__(self, index=None, save_dir=None,
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points=None,
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points_path=None,
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points_db=None,
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points_db_path=None,
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index_path=None,
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include_only_properties=None,
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precision=GEOHASH_PRECISION):
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if save_dir:
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self.save_dir = save_dir
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else:
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self.save_dir = None
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if include_only_properties and hasattr(include_only_properties, '__contains__'):
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self.include_only_properties = include_only_properties
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if not index_path:
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index_path = os.path.join(save_dir or '.', self.INDEX_FILENAME)
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if not index:
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self.index = defaultdict(list)
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else:
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self.index = index
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if not points_path:
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points_path = os.path.join(save_dir or '.', self.POINTS_FILENAME)
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if not points:
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self.points = []
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else:
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self.points = points
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if not points_db_path:
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points_db_path = os.path.join(save_dir or '.', self.POINTS_DB_DIR)
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if not points_db:
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self.points_db = LevelDB(points_db_path)
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else:
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self.points_db = points_db
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self.precision = precision
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self.i = 0
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def index_point(self, lat, lon):
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code = geohash.encode(lat, lon)[:self.precision]
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for key in [code] + geohash.neighbors(code):
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self.index[key].append(self.i)
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self.points.extend([lat, lon])
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def add_point(self, lat, lon, properties, cache=False, include_only_properties=None):
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if include_only_properties is not None:
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properties = {k: v for k, v in properties.iteritems() if k in include_only_properties}
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self.index_point(lat, lon)
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self.points_db.Put(self.properties_key(self.i), json.dumps(properties))
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self.i += 1
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def load_properties(self, filename):
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properties = json.load(open(filename))
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self.i = int(properties.get('num_polygons', self.i))
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self.precision = int(properties.get('precision', self.precision))
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def save_properties(self, out_filename):
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out = open(out_filename, 'w')
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json.dump({'num_polygons': str(self.i),
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'precision': self.precision}, out)
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def save_index(self):
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if not self.index_path:
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self.index_path = os.path.join(self.save_dir or '.', self.INDEX_FILENAME)
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json.dump(self.index, open(self.index_path, 'w'))
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@classmethod
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def load_index(cls, d, index_name=None):
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return json.load(open(os.path.join(d, index_name or cls.INDEX_FILENAME)))
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def save_points(self):
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json.dump(self.points, open(self.points_path, 'w'))
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@classmethod
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def load_points(cls, d):
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return array.array('d', json.load(open(os.path.join(d, cls.POINTS_FILENAME))))
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def properties_key(self, i):
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return 'props:{}'.format(i)
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def get_properties(self, i):
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return self.points_db.Get(self.properties_key(i))
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def save(self):
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self.save_index()
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self.save_properties(os.path.join(self.save_dir, self.PROPS_FILENAME))
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@classmethod
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def load(cls, d):
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index = cls.load_index(d)
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points = cls.load_points(d)
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points_db = LevelDB(os.path.join(d, cls.POINTS_DB_DIR))
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point_index = cls(index=index, points=points, points_db=points_db)
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point_index.load_properties(os.path.join(d, cls.PROPS_FILENAME))
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return point_index
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def get_candidate_points(self, latitude, longitude):
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code = geohash.encode(latitude, longitude)[:self.precision]
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candidates = OrderedDict()
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candidates.update([(k, None) for k in self.index.get(code, [])])
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for neighbor in geohash.neighbors(code):
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candidates.update([(k, None) for k in self.index.get(neighbor, [])])
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return candidates.keys()
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def point_distances(self, latitude, longitude):
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candidates = self.get_candidate_points(latitude, longitude)
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return [(i, self.points[i * 2], self.points[i * 2 + 1],
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haversine_distance(latitude, longitude,
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self.points[i * 2],
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self.points[i * 2 + 1]))
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for i in candidates]
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def all_nearby_points(self, latitude, longitude):
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distances = self.point_distances(latitude, longitude)
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if not distances:
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return []
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return sorted(distances, key=operator.itemgetter(-1))
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def nearest_n_points(self, latitude, longitude, n=2):
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return self.all_nearby_points(latitude, longitude)[:n]
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def nearest_point(self, latitude, longitude):
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distances = self.all_nearby_points(latitude, longitude)
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if not distances:
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return None
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return distances[0]
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