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[root@localhost examples]# python facerec_from_video_file.py
RuntimeError: module compiled against API version 0xa but this version of numpy is 0x7
Traceback (most recent call last):
  File "facerec_from_video_file.py", line 2, in <module>
    import cv2
  File "/usr/lib64/python2.7/site-packages/cv2/__init__.py", line 3, in <module>
    from .cv2 import *
ImportError: numpy.core.multiarray failed to import

Solution:

pip install --upgrade --force-reinstall numpy