if len(bboxes_cls) > 0:
valid_cls[cls] = True
_gt_bboxes = [[None for _ in xrange(n_img)]
for _ in xrange(n_class)]
for i in range(n_img):
for cls in range(n_class):
After Change
if len(bboxes_cls) > 0:
valid_cls[cls] = True
_gt_bboxes = [[None for _ in six.moves.range(n_img)]
for _ in six.moves.range(n_class)]
for i in range(n_img):
for cls in range(n_class):