title: AttributeError with OpenCV in Python
body: <hr>
  
  <pre><code>Traceback (most recent call last):
   File "test.py", line 10, in &lt;module&gt;
    tracker = cv2.Tracker_create("MIL")
  AttributeError: module 'cv2.cv2' has no attribute 'Tracker_create
  </code></pre>
  
  <p>I get the above error when I try to run:</p>
  
  <pre><code>import cv2
  import sys
  
  if __name__ == '__main__' :
  
  # Set up tracker.
  # Instead of MIL, you can also use
  # BOOSTING, KCF, TLD, MEDIANFLOW or GOTURN
  
  tracker = cv2.Tracker_create("MIL")
  
  # Read video
  video = cv2.VideoCapture(0)
  
  # Exit if video not opened.
  if not video.isOpened():
      print ("Could not open video")
      sys.exit()
  
  # Read first frame.
  ok, frame = video.read()
  if not ok:
      print ('Cannot read video file')
      sys.exit()
  
  # Define an initial bounding box
  bbox = (287, 23, 86, 320)
  
  # Uncomment the line below to select a different bounding box
  # bbox = cv2.selectROI(frame, False)
  
  # Initialize tracker with first frame and bounding box
  ok = tracker.init(frame, bbox)
  
  while True:
      # Read a new frame
      ok, frame = video.read()
      if not ok:
          break
  
      # Update tracker
      ok, bbox = tracker.update(frame)
  
      # Draw bounding box
      if ok:
          p1 = (int(bbox[0]), int(bbox[1]))
          p2 = (int(bbox[0] + bbox[2]), int(bbox[1] + bbox[3]))
          cv2.rectangle(frame, p1, p2, (0,0,255))
  
      # Display result
      cv2.imshow("Tracking", frame)
  
      # Exit if ESC pressed
      k = cv2.waitKey(1) &amp; 0xff
      if k == 27 : break
  </code></pre>
  
  <p>I found an answer here: <a href="https://stackoverflow.com/questions/42387322/how-to-add-tracker-in-opencv-python-2-7">How to add &quot;Tracker&quot; in openCV python 2.7</a></p>
  
  <p>But this confused me more. I'm on MacOSX and I'm just getting started with OpenCV and I'm not really sure how to recompile OpenCV with the correct modules.</p>
  
  <p>Thanks in advance, and sorry if I'm missing something obvious.</p>