avoid raising an error when visualizing annotations containing only bboxes cocodataset#495

Author: Christopher Woodall

PythonAPI/pycocotools/coco.py

@@ -239,7 +239,7 @@ def showAnns(self, anns, draw_bbox=False):
         """
         if len(anns) == 0:
             return 0
-        if 'segmentation' in anns[0] or 'keypoints' in anns[0]:
+        if 'bbox' in anns[0] or 'segmentation' in anns[0] or 'keypoints' in anns[0]:
             datasetType = 'instances'
         elif 'caption' in anns[0]:
             datasetType = 'captions'