Add description, simplify input processing in tiles2pb.py

db/tiles2pg.py

@@ -1,7 +1,17 @@
 #!/usr/bin/python3
+
+"""This script takes a file where each line of the form
+
+<count> <lat_x_100> <lon_x_100>
+
+represents the number of OSM nodes in a rectangular tile
+[lat, lon, lat + 0.01, lon + 0.01].
+lat_x_100 is latitude multiplied by 100 and truncated to an integer.
+"""
+
+
 import argparse
 import logging
-import re
 import sys
 
 import psycopg2
@@ -17,31 +27,36 @@ if __name__ == '__main__':
     log_level = logging.INFO if options.verbose else logging.WARNING
     logging.basicConfig(level=log_level, format='%(levelname)s: %(message)s')
 
-    COUNT_LAT_LON_RE = r'^\s*(\d+)\s+(-?\d+)\s+(-?\d+)'
+    TILE_SIDE = 0.01  # degrees
 
     with psycopg2.connect(f'dbname={options.database}') as conn:
         with conn.cursor() as cur:
             cnt = 0
             for line in sys.stdin:
-                m = re.match(COUNT_LAT_LON_RE, line)
-                if m:
-                    (count, lat, lon) = (int(m.group(1)),
-                                         float(m.group(2))/100,
-                                         float(m.group(3))/100)
-                    cur.execute(f'''
+                tokens = line.split()
+                if len(tokens) == 3:
+                    try:
+                        (count, lat, lon) = (int(t) for t in tokens)
+                    except ValueError:
+                        logging.critical(f"Wrong number format at line {cnt}")
+                        conn.rollback()
+                        sys.exit(1)
+
+                    lat /= 100.0
+                    lon /= 100.0
+                    cur.execute(f"""
                         INSERT INTO {options.table} (count, tile) 
                             VALUES (%s,
                                     ST_SetSRID(ST_MakeBox2d(ST_Point(%s, %s),
                                                             ST_Point(%s, %s)),
                                                4326)
                                    )
-                        ''', (count, lon, lat, lon + 0.01, lat + 0.01)
+                        """, (count, lon, lat, lon + TILE_SIDE, lat + TILE_SIDE)
                     )
                     cnt += 1
                 else:
                     logging.warning(f"Incorrect count-lat-lon line '{line}'")
 
-            logging.info('Commit')
+            logging.info("Commit")
             conn.commit()
-            logging.info(f'Uploaded {cnt} tiles')
-
+            logging.info(f"Uploaded {cnt} tiles")