]> git.openstreetmap.org Git - nominatim.git/blob - nominatim/tools/postcodes.py
Merge pull request #2324 from lonvia/generic-external-postcodes
[nominatim.git] / nominatim / tools / postcodes.py
1 """
2 Functions for importing, updating and otherwise maintaining the table
3 of artificial postcode centroids.
4 """
5 import csv
6 import gzip
7 import logging
8 from math import isfinite
9
10 from psycopg2.extras import execute_values
11
12 from nominatim.db.connection import connect
13
14 LOG = logging.getLogger()
15
16 def _to_float(num, max_value):
17     """ Convert the number in string into a float. The number is expected
18         to be in the range of [-max_value, max_value]. Otherwise rises a
19         ValueError.
20     """
21     num = float(num)
22     if not isfinite(num) or num <= -max_value or num >= max_value:
23         raise ValueError()
24
25     return num
26
27 class _CountryPostcodesCollector:
28     """ Collector for postcodes of a single country.
29     """
30
31     def __init__(self, country):
32         self.country = country
33         self.collected = dict()
34
35
36     def add(self, postcode, x, y):
37         """ Add the given postcode to the collection cache. If the postcode
38             already existed, it is overwritten with the new centroid.
39         """
40         self.collected[postcode] = (x, y)
41
42
43     def commit(self, conn, analyzer, project_dir):
44         """ Update postcodes for the country from the postcodes selected so far
45             as well as any externally supplied postcodes.
46         """
47         self._update_from_external(analyzer, project_dir)
48         to_add, to_delete, to_update = self._compute_changes(conn)
49
50         LOG.info("Processing country '%s' (%s added, %s deleted, %s updated).",
51                  self.country, len(to_add), len(to_delete), len(to_update))
52
53         with conn.cursor() as cur:
54             if to_add:
55                 execute_values(cur,
56                                """INSERT INTO location_postcode
57                                       (place_id, indexed_status, country_code,
58                                        postcode, geometry) VALUES %s""",
59                                to_add,
60                                template="""(nextval('seq_place'), 1, '{}',
61                                            %s, 'SRID=4326;POINT(%s %s)')
62                                         """.format(self.country))
63             if to_delete:
64                 cur.execute("""DELETE FROM location_postcode
65                                WHERE country_code = %s and postcode = any(%s)
66                             """, (self.country, to_delete))
67             if to_update:
68                 execute_values(cur,
69                                """UPDATE location_postcode
70                                   SET indexed_status = 2,
71                                       geometry = ST_SetSRID(ST_Point(v.x, v.y), 4326)
72                                   FROM (VALUES %s) AS v (pc, x, y)
73                                   WHERE country_code = '{}' and postcode = pc
74                                """.format(self.country),
75                                to_update)
76
77
78     def _compute_changes(self, conn):
79         """ Compute which postcodes from the collected postcodes have to be
80             added or modified and which from the location_postcode table
81             have to be deleted.
82         """
83         to_update = []
84         to_delete = []
85         with conn.cursor() as cur:
86             cur.execute("""SELECT postcode, ST_X(geometry), ST_Y(geometry)
87                            FROM location_postcode
88                            WHERE country_code = %s""",
89                         (self.country, ))
90             for postcode, x, y in cur:
91                 newx, newy = self.collected.pop(postcode, (None, None))
92                 if newx is not None:
93                     dist = (x - newx)**2 + (y - newy)**2
94                     if dist > 0.0000001:
95                         to_update.append((postcode, newx, newy))
96                 else:
97                     to_delete.append(postcode)
98
99         to_add = [(k, v[0], v[1]) for k, v in self.collected.items()]
100         self.collected = []
101
102         return to_add, to_delete, to_update
103
104
105     def _update_from_external(self, analyzer, project_dir):
106         """ Look for an external postcode file for the active country in
107             the project directory and add missing postcodes when found.
108         """
109         csvfile = self._open_external(project_dir)
110         if csvfile is None:
111             return
112
113         try:
114             reader = csv.DictReader(csvfile)
115             for row in reader:
116                 if 'postcode' not in row or 'lat' not in row or 'lon' not in row:
117                     LOG.warning("Bad format for external postcode file for country '%s'."
118                                 " Ignored.", self.country)
119                     return
120                 postcode = analyzer.normalize_postcode(row['postcode'])
121                 if postcode not in self.collected:
122                     try:
123                         self.collected[postcode] = (_to_float(row['lon'], 180),
124                                                     _to_float(row['lat'], 90))
125                     except ValueError:
126                         LOG.warning("Bad coordinates %s, %s in %s country postcode file.",
127                                     row['lat'], row['lon'], self.country)
128
129         finally:
130             csvfile.close()
131
132
133     def _open_external(self, project_dir):
134         fname = project_dir / '{}_postcodes.csv'.format(self.country)
135
136         if fname.is_file():
137             LOG.info("Using external postcode file '%s'.", fname)
138             return open(fname, 'r')
139
140         fname = project_dir / '{}_postcodes.csv.gz'.format(self.country)
141
142         if fname.is_file():
143             LOG.info("Using external postcode file '%s'.", fname)
144             return gzip.open(fname, 'rt')
145
146         return None
147
148
149 def update_postcodes(dsn, project_dir, tokenizer):
150     """ Update the table of artificial postcodes.
151
152         Computes artificial postcode centroids from the placex table,
153         potentially enhances it with external data and then updates the
154         postcodes in the table 'location_postcode'.
155     """
156     with tokenizer.name_analyzer() as analyzer:
157         with connect(dsn) as conn:
158             # First get the list of countries that currently have postcodes.
159             # (Doing this before starting to insert, so it is fast on import.)
160             with conn.cursor() as cur:
161                 cur.execute("SELECT DISTINCT country_code FROM location_postcode")
162                 todo_countries = set((row[0] for row in cur))
163
164             # Recompute the list of valid postcodes from placex.
165             with conn.cursor(name="placex_postcodes") as cur:
166                 cur.execute("""SELECT country_code, pc, ST_X(centroid), ST_Y(centroid)
167                                FROM (
168                                  SELECT country_code,
169                                         token_normalized_postcode(address->'postcode') as pc,
170                                         ST_Centroid(ST_Collect(ST_Centroid(geometry))) as centroid
171                                  FROM placex
172                                  WHERE address ? 'postcode' and geometry IS NOT null
173                                        and country_code is not null
174                                  GROUP BY country_code, pc) xx
175                                WHERE pc is not null
176                                ORDER BY country_code, pc""")
177
178                 collector = None
179
180                 for country, postcode, x, y in cur:
181                     if collector is None or country != collector.country:
182                         if collector is not None:
183                             collector.commit(conn, analyzer, project_dir)
184                         collector = _CountryPostcodesCollector(country)
185                         todo_countries.discard(country)
186                     collector.add(postcode, x, y)
187
188                 if collector is not None:
189                     collector.commit(conn, analyzer, project_dir)
190
191             # Now handle any countries that are only in the postcode table.
192             for country in todo_countries:
193                 _CountryPostcodesCollector(country).commit(conn, analyzer, project_dir)
194
195             conn.commit()
196
197         analyzer.update_postcodes_from_db()