Use numpy.argpartition():
k = 3np.argpartition(arr, len(arr) - k)[-k:]Adjust k index to whatever you need.
NOTE: returned indices are not guaranteed to be in the "sorted order" - just that anything past index k is larger than the value at position k in the sorted array.
NOTE 2: If you do need the returned indices to be sorted themselves, then simply add a numpy.sort() to the above command:
np.sort(np.argpartition(arr, len(arr) - k)[-k:])numpy.argpartition() provides significant performance gains over full sort especially for large arr. In the above example you do a full sort only over the selected indices (not all).
