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71 lines
1.8 KiB
Python
71 lines
1.8 KiB
Python
"""
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Getting OpenStreetMap data from the web.
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"""
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import logging
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import time
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from dataclasses import dataclass
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from pathlib import Path
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from typing import Dict
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import urllib3
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from map_machine.boundary_box import BoundaryBox
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__author__ = "Sergey Vartanov"
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__email__ = "me@enzet.ru"
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SLEEP_TIME_BETWEEN_REQUESTS: float = 2.0
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@dataclass
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class NetworkError(Exception):
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"""Failed network request."""
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message: str
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def get_osm(
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boundary_box: BoundaryBox, cache_file_path: Path, to_update: bool = False
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) -> str:
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"""
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Download OSM data from the web or get if from the cache.
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:param boundary_box: borders of the map part to download
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:param cache_file_path: cache file to store downloaded OSM data
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:param to_update: update cache files
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"""
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if not to_update and cache_file_path.is_file():
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with cache_file_path.open() as output_file:
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return output_file.read()
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content: bytes = get_data(
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"https://api.openstreetmap.org/api/0.6/map",
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{"bbox": boundary_box.get_format()},
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)
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with cache_file_path.open("bw+") as output_file:
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output_file.write(content)
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return content.decode("utf-8")
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def get_data(address: str, parameters: Dict[str, str]) -> bytes:
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"""
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Construct Internet page URL and get its descriptor.
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:param address: URL without parameters
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:param parameters: URL parameters
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:return: connection descriptor
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"""
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logging.info(f"Getting {address}...")
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pool_manager: urllib3.PoolManager = urllib3.PoolManager()
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urllib3.disable_warnings()
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try:
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result = pool_manager.request("GET", address, parameters)
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except urllib3.exceptions.MaxRetryError:
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raise NetworkError("Cannot download data: too many attempts.")
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pool_manager.clear()
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time.sleep(SLEEP_TIME_BETWEEN_REQUESTS)
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return result.data
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