Efficient way to take the minimum/maximum n values and indices from a matrix using NumPy

Question

What\'s an efficient way, given a NumPy matrix (2D array), to return the minimum/maximum n values (along with their indices) in the array?

Currently I h

Answer 1

Since there is no heap implementation in NumPy, probably your best guess is to sort the whole array and take the last n elements:

def n_max(arr, n):
    indices = arr.ravel().argsort()[-n:]
    indices = (numpy.unravel_index(i, arr.shape) for i in indices)
    return [(arr[i], i) for i in indices]

(This will probably return the list in reverse order compared to your implementation - I did not check.)

A more efficient solution that works with newer versions of NumPy is given in this answer.