N largest values in each row of ndarray

Question

I have an ndarray where each row is a separate histogram. For each row, I wish to find the top N values.

I am aware of a solution for the global top N values (A fas

Answer 1

You can use np.partition in the same way as the question you linked: the sorting is already along the last axis:

In [2]: a = np.array([[ 5,  4,  3,  2,  1],
               [10,  9,  8,  7,  6]])
In [3]: b = np.partition(a, -3)    # top 3 values from each row
In [4]: b[:,-3:]
Out[4]: 
array([[ 3,  4,  5],
       [ 8,  9, 10]])