fix filename storing in prepare_polar_maps

mu_map/data/prepare_polar_maps.py

@@ -180,8 +180,8 @@ if __name__ == "__main__":
         _ac = "ac" if row[headers.ac] else "nac"
         _sc = "sc" if row[headers.sc] else "nsc"
         _file = f"{row[headers.id]:04d}-{_ac}_{_sc}_{row[headers.type]}.png"
-        _file = os.path.join(args.images_dir, _file)
         row[headers.file] = _file
+        _file = os.path.join(args.images_dir, _file)
 
         if (
             len(