sun_position/geo.py

   1 #!/usr/bin/env python
   2 # SPDX-License-Identifier: GPL-2.0-or-later
   3 # Copyright 2010  Maximilian Hoegner <hp.maxi@hoegners.de>.
   4
   5 # geo.py is a python module with no dependencies on extra packages,
   6 # providing some convenience functions for working with geographic
   7 # coordinates
   8
   9 ### Part one - Functions for dealing with points on a sphere ###
  10
  11 ### Part two - A tolerant parser for position strings ###
  12 import re
  13
  14
  15 class Parser:
  16     """ A parser class using regular expressions. """
  17
  18     def __init__(self):
  19         self.patterns = {}
  20         self.raw_patterns = {}
  21         self.virtual = {}
  22
  23     def add(self, name, pattern, virtual=False):
  24         """ Adds a new named pattern (regular expression) that can reference previously added patterns by %(pattern_name)s.
  25         Virtual patterns can be used to make expressions more compact but don't show up in the parse tree. """
  26         self.raw_patterns[name] = "(?:" + pattern + ")"
  27         self.virtual[name] = virtual
  28
  29         try:
  30             self.patterns[name] = ("(?:" + pattern + ")") % self.patterns
  31         except KeyError as e:
  32             raise (Exception, "Unknown pattern name: %s" % str(e))
  33
  34     def parse(self, pattern_name, text):
  35         """ Parses 'text' with pattern 'pattern_name' and returns parse tree """
  36
  37         # build pattern with subgroups
  38         sub_dict = {}
  39         subpattern_names = []
  40         for s in re.finditer(r"%\(.*?\)s", self.raw_patterns[pattern_name]):
  41             subpattern_name = s.group()[2:-2]
  42             if not self.virtual[subpattern_name]:
  43                 sub_dict[subpattern_name] = "(" + self.patterns[
  44                     subpattern_name] + ")"
  45                 subpattern_names.append(subpattern_name)
  46             else:
  47                 sub_dict[subpattern_name] = self.patterns[subpattern_name]
  48
  49         pattern = "^" + (self.raw_patterns[pattern_name] % sub_dict) + "$"
  50
  51         # do matching
  52         m = re.match(pattern, text)
  53
  54         if m == None:
  55             return None
  56
  57         # build tree recursively by parsing subgroups
  58         tree = {"TEXT": text}
  59
  60         for i in range(len(subpattern_names)):
  61             text_part = m.group(i + 1)
  62             if not text_part == None:
  63                 subpattern = subpattern_names[i]
  64                 tree[subpattern] = self.parse(subpattern, text_part)
  65
  66         return tree
  67
  68
  69 position_parser = Parser()
  70 position_parser.add("direction_ns", r"[NSns]")
  71 position_parser.add("direction_ew", r"[EOWeow]")
  72 position_parser.add("decimal_separator", r"[\.,]", True)
  73 position_parser.add("sign", r"[+-]")
  74
  75 position_parser.add("nmea_style_degrees", r"[0-9]{2,}")
  76 position_parser.add("nmea_style_minutes",
  77                     r"[0-9]{2}(?:%(decimal_separator)s[0-9]*)?")
  78 position_parser.add(
  79     "nmea_style", r"%(sign)s?\s*%(nmea_style_degrees)s%(nmea_style_minutes)s")
  80
  81 position_parser.add(
  82     "number",
  83     r"[0-9]+(?:%(decimal_separator)s[0-9]*)?|%(decimal_separator)s[0-9]+")
  84
  85 position_parser.add("plain_degrees", r"(?:%(sign)s\s*)?%(number)s")
  86
  87 position_parser.add("degree_symbol", r"°", True)
  88 position_parser.add("minutes_symbol", r"'|′|`|´", True)
  89 position_parser.add("seconds_symbol",
  90                     r"%(minutes_symbol)s%(minutes_symbol)s|″|\"",
  91                     True)
  92 position_parser.add("degrees", r"%(number)s\s*%(degree_symbol)s")
  93 position_parser.add("minutes", r"%(number)s\s*%(minutes_symbol)s")
  94 position_parser.add("seconds", r"%(number)s\s*%(seconds_symbol)s")
  95 position_parser.add(
  96     "degree_coordinates",
  97     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"
  98 )
  99
 100 position_parser.add(
 101     "coordinates_ns",
 102     r"%(nmea_style)s|%(plain_degrees)s|%(degree_coordinates)s")
 103 position_parser.add(
 104     "coordinates_ew",
 105     r"%(nmea_style)s|%(plain_degrees)s|%(degree_coordinates)s")
 106
 107 position_parser.add(
 108     "position", (
 109         r"\s*%(direction_ns)s\s*%(coordinates_ns)s[,;\s]*%(direction_ew)s\s*%(coordinates_ew)s\s*|"
 110         r"\s*%(direction_ew)s\s*%(coordinates_ew)s[,;\s]*%(direction_ns)s\s*%(coordinates_ns)s\s*|"
 111         r"\s*%(coordinates_ns)s\s*%(direction_ns)s[,;\s]*%(coordinates_ew)s\s*%(direction_ew)s\s*|"
 112         r"\s*%(coordinates_ew)s\s*%(direction_ew)s[,;\s]*%(coordinates_ns)s\s*%(direction_ns)s\s*|"
 113         r"\s*%(coordinates_ns)s[,;\s]+%(coordinates_ew)s\s*"
 114     ))
 115
 116
 117 def get_number(b):
 118     """ Takes appropriate branch of parse tree and returns float. """
 119     s = b["TEXT"].replace(",", ".")
 120     return float(s)
 121
 122
 123 def get_coordinate(b):
 124     """ Takes appropriate branch of the parse tree and returns degrees as a float. """
 125
 126     r = 0.
 127
 128     if b.get("nmea_style"):
 129         if b["nmea_style"].get("nmea_style_degrees"):
 130             r += get_number(b["nmea_style"]["nmea_style_degrees"])
 131         if b["nmea_style"].get("nmea_style_minutes"):
 132             r += get_number(b["nmea_style"]["nmea_style_minutes"]) / 60.
 133         if b["nmea_style"].get(
 134                 "sign") and b["nmea_style"]["sign"]["TEXT"] == "-":
 135             r *= -1.
 136     elif b.get("plain_degrees"):
 137         r += get_number(b["plain_degrees"]["number"])
 138         if b["plain_degrees"].get(
 139                 "sign") and b["plain_degrees"]["sign"]["TEXT"] == "-":
 140             r *= -1.
 141     elif b.get("degree_coordinates"):
 142         if b["degree_coordinates"].get("degrees"):
 143             r += get_number(b["degree_coordinates"]["degrees"]["number"])
 144         if b["degree_coordinates"].get("minutes"):
 145             r += get_number(b["degree_coordinates"]["minutes"]["number"]) / 60.
 146         if b["degree_coordinates"].get("seconds"):
 147             r += get_number(
 148                 b["degree_coordinates"]["seconds"]["number"]) / 3600.
 149         if b["degree_coordinates"].get(
 150                 "sign") and b["degree_coordinates"]["sign"]["TEXT"] == "-":
 151             r *= -1.
 152
 153     return r
 154
 155
 156 def parse_position(s):
 157     """ Takes a (utf8-encoded) string describing a position and returns a tuple of floats for latitude and longitude in degrees.
 158     Tries to be as tolerant as possible with input. Returns None if parsing doesn't succeed. """
 159
 160     parse_tree = position_parser.parse("position", s)
 161     if parse_tree == None: return None
 162
 163     lat_sign = +1.
 164     if parse_tree.get(
 165             "direction_ns") and parse_tree["direction_ns"]["TEXT"] in ("S",
 166                                                                        "s"):
 167         lat_sign = -1.
 168
 169     lon_sign = +1.
 170     if parse_tree.get(
 171             "direction_ew") and parse_tree["direction_ew"]["TEXT"] in ("W",
 172                                                                        "w"):
 173         lon_sign = -1.
 174
 175     lat = lat_sign * get_coordinate(parse_tree["coordinates_ns"])
 176     lon = lon_sign * get_coordinate(parse_tree["coordinates_ew"])
 177
 178     return lat, lon