Merge pull request #855 from borglab/SFMdata-add-type-hints

clean up SFMdata python module

python/gtsam/examples/SFMdata.py

@@ -5,36 +5,39 @@
 """
 # pylint: disable=invalid-name, E1101
 
+from typing import List
+
 import numpy as np
 
 import gtsam
+from gtsam import Cal3_S2, Point3, Pose3
 
 
-def createPoints():
+def createPoints() -> List[Point3]:
     # Create the set of ground-truth landmarks
-    points = [gtsam.Point3(10.0, 10.0, 10.0),
-              gtsam.Point3(-10.0, 10.0, 10.0),
-              gtsam.Point3(-10.0, -10.0, 10.0),
-              gtsam.Point3(10.0, -10.0, 10.0),
-              gtsam.Point3(10.0, 10.0, -10.0),
-              gtsam.Point3(-10.0, 10.0, -10.0),
-              gtsam.Point3(-10.0, -10.0, -10.0),
-              gtsam.Point3(10.0, -10.0, -10.0)]
+    points = [
+        Point3(10.0, 10.0, 10.0),
+        Point3(-10.0, 10.0, 10.0),
+        Point3(-10.0, -10.0, 10.0),
+        Point3(10.0, -10.0, 10.0),
+        Point3(10.0, 10.0, -10.0),
+        Point3(-10.0, 10.0, -10.0),
+        Point3(-10.0, -10.0, -10.0),
+        Point3(10.0, -10.0, -10.0),
+    ]
     return points
 
 
-def createPoses(K):
-    # Create the set of ground-truth poses
+def createPoses(K: Cal3_S2) -> List[Pose3]:
+    """Generate a set of ground-truth camera poses arranged in a circle about the origin."""
     radius = 40.0
     height = 10.0
-    angles = np.linspace(0, 2*np.pi, 8, endpoint=False)
+    angles = np.linspace(0, 2 * np.pi, 8, endpoint=False)
     up = gtsam.Point3(0, 0, 1)
     target = gtsam.Point3(0, 0, 0)
     poses = []
     for theta in angles:
-        position = gtsam.Point3(radius*np.cos(theta),
-                                radius*np.sin(theta),
-                                height)
+        position = gtsam.Point3(radius * np.cos(theta), radius * np.sin(theta), height)
         camera = gtsam.PinholeCameraCal3_S2.Lookat(position, target, up, K)
         poses.append(camera.pose())
     return poses