np.searchSorted over 2D array

Wed Dec 9 11:06:59 EST 2015

Dear all, 
I need to check whether two 2d numpy arrays have intersections and if so I will need to have the cell indices of the intersection.
By intersection, I exactly mean the intersection definition used in set theory.
I will give an example of what I need to do:
a=[[0,1,2],[3,4,5],[6,7,8]]
b=[[0,1,2],[3,4,5]]
I would like to check whether b is subset of a and then get the indices in a where b matches. 
cellindices=[[True,True,True],[True,True,True],[False,False,False]]
What is the best way to do this in numpy? 

Thanks in Advance for your help, 