import numpy as np
import scipy as scp

• np.flatnonzero # return indices that are non-zero in the flattened version of a.
  This is equivalent to a.ravel().nonzero()[0].

  see also
  nonzero
  Return the indices of the non-zero elements of the input array.
  ravel
  Return a 1-D array containing the elements of the input array.

• **numpy.random.choice(a, size=None, replace=True, p=None) #Generates a random sample from a given 1-D array

  a 1-D array-like or int
  If an ndarray, a random sample is generated from its elements. If an int, the random sample is generated as if a was np.arange(n)

• ** numpy.argsort(a, axis=-1, kind=’quicksort’, order=None)[source]
  Returns the indices that would sort an array.

• np.random.permutation
• np.array_split
• np.vstack