[coordinates] sticking latlon_to_decimal in its own module, adding missing methods

scripts/geodata/coordinates/conversion.py

@@ -0,0 +1,90 @@
+# -*- coding: utf-8 -*-
+'''
+geodata.coordinates.conversion
+------------------------------
+
+Geographic coordinates typically come in two flavors: decimal and
+DMS (degree-minute-second). This module parses a coordinate string
+in just about any format. This was originally created for parsing
+lat/lons found on the web.
+
+Usage:
+    >>> latlon_to_decimal('40°42′46″N', '74°00′21″W') # returns (40.71277777777778, 74.00583333333333)
+    >>> latlon_to_decimal('40,74 N', '74,001 W') # returns (40.74, -74.001)
+'''
+
+import re
+
+from geodata.encoding import safe_decode
+
+beginning_re = re.compile('^[^0-9\-]+', re.UNICODE)
+end_re = re.compile('[^0-9]+$', re.UNICODE)
+
+latitude_dms_regex = re.compile(ur'^(-?[0-9]{1,2})[ ]*[ :°ºd][ ]*([0-5]?[0-9])?[ ]*[:\'\u2032m]?[ ]*([0-5]?[0-9](?:\.\d+)?)?[ ]*[:\?\"\u2033s]?[ ]*(N|n|S|s)?$', re.I | re.UNICODE)
+longitude_dms_regex = re.compile(ur'^(-?1[0-8][0-9]|0?[0-9]{1,2})[ ]*[ :°ºd][ ]*([0-5]?[0-9])?[ ]*[:\'\u2032m]?[ ]*([0-5]?[0-9](?:\.\d+)?)?[ ]*[:\?\"\u2033s]?[ ]*(E|e|W|w)?$', re.I | re.UNICODE)
+
+latitude_decimal_with_direction_regex = re.compile('^(-?[0-9][0-9](?:\.[0-9]+))[ ]*[ :°ºd]?[ ]*(N|n|S|s)$', re.I)
+longitude_decimal_with_direction_regex = re.compile('^(-?1[0-8][0-9]|0?[0-9][0-9](?:\.[0-9]+))[ ]*[ :°ºd]?[ ]*(E|e|W|w)$', re.I)
+
+direction_sign_map = {'n': 1, 's': -1, 'e': 1, 'w': -1}
+
+
+def direction_sign(d):
+    if d is None:
+        return 1
+    d = d.lower().strip()
+    if d in direction_sign_map:
+        return direction_sign_map[d]
+    else:
+        raise ValueError('Invalid direction: {}'.format(d))
+
+
+def degrees_to_decimal(degrees, minutes, seconds):
+    return degrees + (minutes / 60.0) + (seconds / 3600.0)
+
+
+def latlon_to_decimal(latitude, longitude):
+    have_lat = False
+    have_lon = False
+
+    latitude = safe_decode(latitude).strip(u' ,;|')
+    longitude = safe_decode(longitude).strip(u' ,;|')
+
+    latitude = latitude.replace(u',', u'.')
+    longitude = longitude.replace(u',', u'.')
+
+    lat_dms = latitude_dms_regex.match(latitude)
+    lat_dir = latitude_decimal_with_direction_regex.match(latitude)
+
+    if lat_dms:
+        d, m, s, c = lat_dms.groups()
+        sign = direction_sign(c)
+        latitude = degrees_to_decimal(int(d or 0), int(m or 0), int(s or 0))
+        have_lat = True
+    elif lat_dir:
+        d, c = lat_dir.groups()
+        sign = direction_sign(c)
+        latitude = float(d) * sign
+        have_lat = True
+    else:
+        latitude = re.sub(beginning_re, u'', latitude)
+        latitude = re.sub(end_re, u'', latitude)
+
+    lon_dms = longitude_dms_regex.match(longitude)
+    lon_dir = longitude_decimal_with_direction_regex.match(longitude)
+
+    if lon_dms:
+        d, m, s, c = lon_dms.groups()
+        sign = direction_sign(c)
+        longitude = degrees_to_decimal(int(d or 0), int(m or 0), int(s or 0))
+        have_lon = True
+    elif lon_dir:
+        d, c = lon_dir.groups()
+        sign = direction_sign(c)
+        longitude = float(d) * sign
+        have_lon = True
+    else:
+        longitude = re.sub(beginning_re, u'', longitude)
+        longitude = re.sub(end_re, u'', longitude)
+
+    return float(latitude), float(longitude)