179 lines
6.6 KiB
Python
179 lines
6.6 KiB
Python
#!/usr/bin/env python
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# SPDX-License-Identifier: GPL-2.0-or-later
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# Copyright 2010 Maximilian Hoegner <hp.maxi@hoegners.de>.
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# geo.py is a python module with no dependencies on extra packages,
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# providing some convenience functions for working with geographic
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# coordinates
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### Part one - Functions for dealing with points on a sphere ###
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### Part two - A tolerant parser for position strings ###
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import re
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class Parser:
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""" A parser class using regular expressions. """
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def __init__(self):
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self.patterns = {}
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self.raw_patterns = {}
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self.virtual = {}
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def add(self, name, pattern, virtual=False):
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""" Adds a new named pattern (regular expression) that can reference previously added patterns by %(pattern_name)s.
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Virtual patterns can be used to make expressions more compact but don't show up in the parse tree. """
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self.raw_patterns[name] = "(?:" + pattern + ")"
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self.virtual[name] = virtual
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try:
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self.patterns[name] = ("(?:" + pattern + ")") % self.patterns
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except KeyError as e:
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raise (Exception, "Unknown pattern name: %s" % str(e))
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def parse(self, pattern_name, text):
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""" Parses 'text' with pattern 'pattern_name' and returns parse tree """
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# build pattern with subgroups
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sub_dict = {}
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subpattern_names = []
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for s in re.finditer(r"%\(.*?\)s", self.raw_patterns[pattern_name]):
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subpattern_name = s.group()[2:-2]
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if not self.virtual[subpattern_name]:
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sub_dict[subpattern_name] = "(" + self.patterns[
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subpattern_name] + ")"
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subpattern_names.append(subpattern_name)
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else:
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sub_dict[subpattern_name] = self.patterns[subpattern_name]
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pattern = "^" + (self.raw_patterns[pattern_name] % sub_dict) + "$"
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# do matching
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m = re.match(pattern, text)
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if m == None:
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return None
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# build tree recursively by parsing subgroups
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tree = {"TEXT": text}
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for i in range(len(subpattern_names)):
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text_part = m.group(i + 1)
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if not text_part == None:
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subpattern = subpattern_names[i]
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tree[subpattern] = self.parse(subpattern, text_part)
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return tree
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position_parser = Parser()
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position_parser.add("direction_ns", r"[NSns]")
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position_parser.add("direction_ew", r"[EOWeow]")
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position_parser.add("decimal_separator", r"[\.,]", True)
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position_parser.add("sign", r"[+-]")
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position_parser.add("nmea_style_degrees", r"[0-9]{2,}")
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position_parser.add("nmea_style_minutes",
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r"[0-9]{2}(?:%(decimal_separator)s[0-9]*)?")
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position_parser.add(
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"nmea_style", r"%(sign)s?\s*%(nmea_style_degrees)s%(nmea_style_minutes)s")
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position_parser.add(
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"number",
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r"[0-9]+(?:%(decimal_separator)s[0-9]*)?|%(decimal_separator)s[0-9]+")
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position_parser.add("plain_degrees", r"(?:%(sign)s\s*)?%(number)s")
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position_parser.add("degree_symbol", r"°", True)
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position_parser.add("minutes_symbol", r"'|′|`|´", True)
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position_parser.add("seconds_symbol",
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r"%(minutes_symbol)s%(minutes_symbol)s|″|\"",
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True)
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position_parser.add("degrees", r"%(number)s\s*%(degree_symbol)s")
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position_parser.add("minutes", r"%(number)s\s*%(minutes_symbol)s")
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position_parser.add("seconds", r"%(number)s\s*%(seconds_symbol)s")
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position_parser.add(
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"degree_coordinates",
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r"(?:%(sign)s\s*)?%(degrees)s(?:[+\s]*%(minutes)s)?(?:[+\s]*%(seconds)s)?|(?:%(sign)s\s*)%(minutes)s(?:[+\s]*%(seconds)s)?|(?:%(sign)s\s*)%(seconds)s"
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)
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position_parser.add(
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"coordinates_ns",
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r"%(nmea_style)s|%(plain_degrees)s|%(degree_coordinates)s")
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position_parser.add(
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"coordinates_ew",
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r"%(nmea_style)s|%(plain_degrees)s|%(degree_coordinates)s")
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position_parser.add(
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"position", (
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r"\s*%(direction_ns)s\s*%(coordinates_ns)s[,;\s]*%(direction_ew)s\s*%(coordinates_ew)s\s*|"
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r"\s*%(direction_ew)s\s*%(coordinates_ew)s[,;\s]*%(direction_ns)s\s*%(coordinates_ns)s\s*|"
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r"\s*%(coordinates_ns)s\s*%(direction_ns)s[,;\s]*%(coordinates_ew)s\s*%(direction_ew)s\s*|"
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r"\s*%(coordinates_ew)s\s*%(direction_ew)s[,;\s]*%(coordinates_ns)s\s*%(direction_ns)s\s*|"
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r"\s*%(coordinates_ns)s[,;\s]+%(coordinates_ew)s\s*"
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))
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def get_number(b):
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""" Takes appropriate branch of parse tree and returns float. """
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s = b["TEXT"].replace(",", ".")
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return float(s)
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def get_coordinate(b):
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""" Takes appropriate branch of the parse tree and returns degrees as a float. """
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r = 0.
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if b.get("nmea_style"):
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if b["nmea_style"].get("nmea_style_degrees"):
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r += get_number(b["nmea_style"]["nmea_style_degrees"])
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if b["nmea_style"].get("nmea_style_minutes"):
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r += get_number(b["nmea_style"]["nmea_style_minutes"]) / 60.
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if b["nmea_style"].get(
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"sign") and b["nmea_style"]["sign"]["TEXT"] == "-":
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r *= -1.
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elif b.get("plain_degrees"):
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r += get_number(b["plain_degrees"]["number"])
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if b["plain_degrees"].get(
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"sign") and b["plain_degrees"]["sign"]["TEXT"] == "-":
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r *= -1.
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elif b.get("degree_coordinates"):
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if b["degree_coordinates"].get("degrees"):
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r += get_number(b["degree_coordinates"]["degrees"]["number"])
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if b["degree_coordinates"].get("minutes"):
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r += get_number(b["degree_coordinates"]["minutes"]["number"]) / 60.
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if b["degree_coordinates"].get("seconds"):
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r += get_number(
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b["degree_coordinates"]["seconds"]["number"]) / 3600.
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if b["degree_coordinates"].get(
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"sign") and b["degree_coordinates"]["sign"]["TEXT"] == "-":
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r *= -1.
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return r
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def parse_position(s):
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""" Takes a (utf8-encoded) string describing a position and returns a tuple of floats for latitude and longitude in degrees.
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Tries to be as tolerant as possible with input. Returns None if parsing doesn't succeed. """
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parse_tree = position_parser.parse("position", s)
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if parse_tree == None: return None
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lat_sign = +1.
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if parse_tree.get(
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"direction_ns") and parse_tree["direction_ns"]["TEXT"] in ("S",
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"s"):
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lat_sign = -1.
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lon_sign = +1.
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if parse_tree.get(
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"direction_ew") and parse_tree["direction_ew"]["TEXT"] in ("W",
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"w"):
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lon_sign = -1.
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lat = lat_sign * get_coordinate(parse_tree["coordinates_ns"])
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lon = lon_sign * get_coordinate(parse_tree["coordinates_ew"])
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return lat, lon
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