fixed issues

skais/ais/ais_trajectory.py

@@ -236,6 +236,13 @@ class AISTrajectory(AISPoints):
         positions = self.df[['longitude', 'latitude']].to_numpy()
         min_lon, max_lon = (min(positions[:, 0]), max(positions[:, 0]))
         min_lat, max_lat = (min(positions[:, 1]), max(positions[:, 1]))
+        if min_lat == max_lat:
+            min_lat -= 1
+            max_lat += 1
+        if min_lon == max_lon:
+            min_lon -= 1
+            max_lon += 1
+
         for longitude, latitude in positions:
             x_coord, y_coord = get_coord(latitude, longitude, height, width, min_lat, max_lat, min_lon, max_lon)