add: take into account reference cardinal direction

util/import_photos.py

@@ -10,9 +10,11 @@ from fractions import Fraction
 import sqlite3
 
 
-def decimal_from_rational64u(dms: str):
+def decimal_from_rational64u(dms: str, ref):
     """Convert coordinates from rational64u EXIF uses to represent
     degrees, minutes, and seconds of a point to decimal format
+    Take into account reference cardinal direction and
+    turn [S]outh and [W]est coordinates negative
 
     General formula is
     dec_degree = degreesNumerator / degreesDenominator
@@ -22,8 +24,8 @@ def decimal_from_rational64u(dms: str):
     https://en.wikipedia.org/wiki/Geographic_coordinate_conversion
     https://gis.stackexchange.com/questions/136925/how-to-parse-exif-gps-information-to-lat-lng-decimal-numbers
 
-    >>> decimal_from_rational64u(dms="42/1, 18/1, 2914/100")
-    42.30809
+    >>> decimal_from_rational64u(dms="42/1, 18/1, 2914/100", "S")
+    -42.30809
     """
 
     # 1 split by comma
@@ -33,7 +35,7 @@ def decimal_from_rational64u(dms: str):
     # 5 sum up the result
     # 6 convert to decimal
     # 7 round to 5th decimal point
-    return round(
+    dec_coordinates = round(
         float(
             sum(
                 a / b
@@ -42,6 +44,10 @@ def decimal_from_rational64u(dms: str):
         ),
         5,
     )
+    if ref in ("S", "W"):
+        dec_coordinates = -dec_coordinates
+
+    return dec_coordinates
 
 
 def process_pictures(source: str, dest_shrunk: str, dest_original: str):
@@ -88,10 +94,12 @@ def process_pictures(source: str, dest_shrunk: str, dest_original: str):
                 "ResizedImage": path.join(dest_shrunk, filename),
                 "OriginalImage": path.join(dest_original, filename),
                 "DateTimeOriginal": exif["DateTimeOriginal"],  # Q: normalize it?
-                "GPSLatitude": decimal_from_rational64u(exif["GPSLatitude"]),
-                "GPSLatitudeRef": exif["GPSLatitudeRef"],
-                "GPSLongitude": decimal_from_rational64u(exif["GPSLongitude"]),
-                "GPSLongitudeRef": exif["GPSLongitudeRef"],
+                "GPSLatitude": decimal_from_rational64u(
+                    exif["GPSLatitude"], exif["GPSLatitudeRef"]
+                ),
+                "GPSLongitude": decimal_from_rational64u(
+                    exif["GPSLongitude"], exif["GPSLongitudeRef"]
+                ),
             }
         except KeyError as e:
             print(f"Image '{filename}' has no valid exif")