cv2 line change from horizontal to vertical [closed]

Question

I am trying to figure out how to change a line drawn in cv2 in some code from horizontal to vertical. It comes out horizontal with this:

cv2.line(frame, (0, H // 2), (W, H // 2), (0, 255, 255), 2)

How to change to vertical?

I understand the line starts with parameter (0, H // 2) and ends with (W, H // 2) but its puzzling to me how to change it around from horizontal coordinate definition to vertical. Some experimentations with this have been unsuccessful and tips GREATLY appreciated.

H & W are defined to have a maximum of 500 pixels defined here:

# loop over frames from the video stream
while True:
    # grab the next frame and handle if we are reading from either
    # VideoCapture or VideoStream
    frame = vs.read()
    frame = frame[1] if args.get("input", False) else frame

    # if we are viewing a video and we did not grab a frame then we
    # have reached the end of the video
    if args["input"] is not None and frame is None:
        break

    # resize the frame to have a maximum width of 500 pixels (the
    # less data we have, the faster we can process it), then convert
    # the frame from BGR to RGB for dlib
    frame = imutils.resize(frame, width=500)
    rgb = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)

    # if the frame dimensions are empty, set them
    if W is None or H is None:
        (H, W) = frame.shape[:2]