Improvements to coordinate argument parsing.

Handle a range of formats that include the output of exiftool
and jhead, to make it easier to use pytopo to show the location
of a GPS-tagged photo.

Update the argparsing unit test to test those cases,
plus some examples in east/south quadrants.

pytopo/MapUtils.py

@@ -97,30 +97,56 @@ def to_decimal_degrees(coord, degformat="DD"):
     except:
         pass
 
-    # Format used in EXIF in Pixel phone cameras
-    # e.g. 35 deg 54' 35.67" N, 106 deg 16' 10.78" W
-    # which is also the format handled by exiftool.
-    # Also handles a form with an actual degree symbol,
-    # like 106° 16' 10.78" W, or a ^ in place of the degree symbol.
-    DMS_COORD_PAT = "\s*([+-]?[0-9]{1,3})\s*(?:deg|°|\^)" \
-                    "\s*([0-9]{1,3})'\s*" \
-                    "([0-9]{1,3})(.[0-9]+\")?\s*([NSEW])?"
-    m = re.match(DMS_COORD_PAT, coord)
+    # Match the following formats and variants:
+    # jhead, for EXIF from photos:    N 35d 51m 21.08s
+    # exiftool for EXIF from photos:  35 deg 51' 21.08" N
+    # More general format:            35° 54' 35.67" N, 106 deg 16' 10.78" W
+    # For degrees, accept deg d ° ^
+    # For minutes, accept ' min m
+    # For seconds, accept " sec s
+    # NSEW can either begin or end the string, or may be missing entirely,
+    # in which case positive means north/east.
+    # Degrees may start with a + or -
+    coord_pat = r"\s*([NSEW])?\s*([+-]?[0-9]{1,3})\s*(?:deg|d|°|\^)" \
+        r"\s*([0-9]{1,3})(?:'|m|min)\s*" \
+        r"([0-9]{1,3})(.[0-9]+)?\s*(?:\"|s|sec)\s*([NSEW])?"
+    m = re.match(coord_pat, coord)
     if m:
-        deg, mins, secs, subsecs, direc = m.groups()
+        direc1, deg, mins, secs, subsecs, direc2 = m.groups()
+        if direc1 and direc2 and direc1 != direc2:
+            print("%s: Conflicting directions, %s vs %s" % (coord,
+                                                            direc1, direc2),
+                  file=sys.stderr)
+            raise ValueError("Can't parse '%s' as a coordinate" % coord)
+
+        # Sign fiddling: end up with positive value but save the sign
+        if direc2 and not direc1:
+            direc1 = direc2
+        if direc1 == 'S' or direc1 == 'W':
+            sign = -1
+        else:
+            sign = 1
+        val = int(deg) * sign
+        if val < 0:
+            sign = -1
+            val = -val
+        else:
+            sign = 1
+
         secs = float(secs)
         if subsecs:
             if subsecs.endswith('"'):
                 subsecs = subsecs[:-1]
             secs += float(subsecs)
         mins = int(mins) + secs/60.
-        val = int(deg)
         if val >= 0:
             val += mins/60.
         else:
             val -= mins/60.
-        if direc == 'S' or direc == 'W':
-            val = -val
+
+        # Restore the sign
+        val *= sign
+        # print("Parsed", coord, "to", val)
         return val
 
     raise ValueError("Can't parse '%s' as a coordinate" % coord)

test/test_argparsing.py

@@ -142,13 +142,36 @@ def test_gpx_plus_overlay(self):
                                 -106.2283611, 35.895508))
 
     def test_explicit_coords(self):
-        args = [ 'pytopo', '37.537', '-122.37' ]
-
-        mapwin =  MapWindow(self.viewer)
-        self.viewer.parse_args(mapwin, args)
+        argslists = [
+            # Several syntax variants for the same location:
+            # decimal degrees syntax
+            ( [ 'pytopo', '37.537', '-122.37' ],
+              [ 37.537, -122.37] ),
+            # exiftool (and most normal humans) syntax
+            ( [ 'pytopo',
+                '37 deg 32\' 13.12" N', '122° 22\' 12.0" W' ],
+              [ 37.537, -122.37] ),
+            # jhead syntax
+            ( [ 'pytopo', 'N 37d 32m 13.12s', 'W 122d 22m 12.0s' ],
+              [ 37.537, -122.37] ),
+
+            # east and south
+            ( [ 'pytopo',
+                '37 deg 32\' 13.12" S', '122° 22\' 12.0" E' ],
+              [ -37.537, 122.37] ),
+            # negative signs
+            ( [ 'pytopo',
+                '-37 deg 32\' 13.12"', '-122° 22\' 12.0" E' ],
+              [ -37.537, -122.37] ),
+        ]
+
+        for argtuple in argslists:
+            args, realcoords = argtuple
+            mapwin =  MapWindow(self.viewer)
+            self.viewer.parse_args(mapwin, args)
 
-        assertCloseEnough(mapwin.center_lon, -122.37)
-        assertCloseEnough(mapwin.center_lat, 37.537)
+            assertCloseEnough(mapwin.center_lat, realcoords[0])
+            assertCloseEnough(mapwin.center_lon, realcoords[1])
 
     def test_explicit_coords_plus_gpx(self):
         args = [ 'pytopo', '35.85', '-106.4',
@@ -227,3 +250,4 @@ def test_known_site_plus_overlay(self):
 
         assertCloseEnough(mapwin.center_lon, sitelon)
         assertCloseEnough(mapwin.center_lat, sitelat)
+