Merge pull request 'Fix and simplify rate calculation' (#15) from w2/photovoter_backend:rate-calculation-fix into main

Reviewed-on: https://git.iamonlyherefortheicecream.ml/DIWHY/photovoter_backend/pulls/15

main.py

@@ -166,15 +166,16 @@ async def photo_points():
     """Get points with the url of a photo and the rate"""
     # assume we always have at least some photos
     # fetch them all
+    # if frontend uses 1 and 0 to represent like and dislike
+    # we can just take the average and turn it into %
+    # 100 * AVG(marks.mark)
     cur.execute(
         """SELECT images.imgid, resizedpath, GPSLatitude, GPSLongitude, 
-                    100*SUM(marks.mark)/COUNT(marks.mark)/MAX(marks.mark)
+                    100 * AVG(marks.mark)
                 FROM images
                 LEFT JOIN marks ON images.imgid = marks.imgid
                 GROUP BY images.imgid;
-        """,  # 100 * SUM(marks.mark)/COUNT(marks.mark)/MAX(marks.mark)
-        # is an ad-hoc percentage of likes without know how front end defined like/dislike
-        # returns None with no marks (sqlite handles division by 0 gracefully)
+        """,
     )
     points = cur.fetchall()
     return [
@@ -183,7 +184,7 @@ async def photo_points():
             "url": point["resizedpath"],
             "lon": point["GPSLongitude"],
             "lat": point["GPSLatitude"],
-            "rate": point["100*SUM(marks.mark)/COUNT(marks.mark)/MAX(marks.mark)"],
+            "rate": point["100 * AVG(marks.mark)"],
         }
         for point in points
     ]

util/import_photos.py

@@ -6,9 +6,50 @@ import filetype
 from os import path, walk
 from sys import argv, stderr
 from shutil import move
+from fractions import Fraction
 import sqlite3
 
 
+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
+                 + minutesNumerator / minutesDenominator / 60
+                 + secondsNumerator / secondsDenominator / 3600
+
+    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", "S")
+    -42.30809
+    """
+
+    # 1 split by comma
+    # 2 turn each into Fraction
+    # 3 zip fractions with their respective (degrees, minutes, seconds) denominator
+    # 4 divide the fraction
+    # 5 sum up the result
+    # 6 convert to decimal
+    # 7 round to 5th decimal point
+    dec_coordinates = round(
+        float(
+            sum(
+                a / b
+                for (a, b) in zip((Fraction(f) for f in dms.split(",")), (1, 60, 3600))
+            )
+        ),
+        5,
+    )
+    if ref in ("S", "W"):
+        dec_coordinates = -dec_coordinates
+
+    return dec_coordinates
+
+
 def process_pictures(source: str, dest_shrunk: str, dest_original: str):
     """Process images from the base directory in the first command line argument.
     Place the resized copies to dest_shrunk and
@@ -32,8 +73,14 @@ def process_pictures(source: str, dest_shrunk: str, dest_original: str):
                 (k[5:], v) for k, v in image.metadata.items() if k.startswith("exif:")
             )
             with image.clone() as cloned:
+                # adjust an image so that its orientation is suitable for viewing
+                # (i.e. top-left orientation) by checking EXIF data
+                cloned.auto_orient()
+                # strip an image of all profiles and comments
                 cloned.strip()  # Q: may damage icc, do we allow that or use smh else?
-                cloned.transform(resize="50%")  # Q: what do we want here?
+                # resize the shorter side to be no more than 1000px
+                # https://legacy.imagemagick.org/discourse-server/viewtopic.php?p=44329#p44329
+                cloned.transform(resize="1000^>")  # Q: what do we want here?
                 # move them to the processed folder
                 cloned.save(filename=path.join(dest_shrunk, filename))
 
@@ -47,10 +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": exif["GPSLatitude"],
-                "GPSLatitudeRef": exif["GPSLatitudeRef"],
-                "GPSLongitude": 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")
@@ -72,18 +121,14 @@ def update_database(pic_info: dict, db_location: str):
         """INSERT INTO images(resizedpath, 
                             origpath, 
                             date, 
-                            GPSLatitude, 
-                            GPSLatitudeRef, 
-                            GPSLongitude, 
-                            GPSLongitudeRef)
+                            GPSLatitude,
+                            GPSLongitude)
 
         VALUES             (:ResizedImage, 
                             :OriginalImage, 
                             :DateTimeOriginal, 
                             :GPSLatitude, 
-                            :GPSLatitudeRef, 
-                            :GPSLongitude, 
-                            :GPSLongitudeRef)
+                            :GPSLongitude)
     """,
         pic_info,
     )
@@ -114,10 +159,8 @@ def check_database(database_path: str):
                     resizedpath TEXT NOT NULL,
                     origpath TEXT NOT NULL,
                     date TEXT,  
-                    GPSLatitude TEXT,  
-                    GPSLatitudeRef TEXT,  
-                    GPSLongitude TEXT, 
-                    GPSLongitudeRef TEXT
+                    GPSLatitude REAL,  
+                    GPSLongitude REAL 
                     )"""
         )
         con.commit()