Create an array with seven random integers from -3 to 3 with a seed of 42:

>>> a = np.random.random_integers(-3, 3, 7)
>>> a
array([ 1,  0, -1,  2,  1, -2,  0])

When we talk about random numbers in programming, we usually talk about pseudo-random numbers (see https://www.khanacademy.org/computing/computer-science/cryptography/crypt/v/random-vs-pseudorandom-number-generators). The numbers appear random, but in fact are calculated using a seed.

Apply the at() method of the sign() universal function to the fourth and sixth array elements:

>>> np.sign.at(a, [3, 5])
>>> a
array([ 1, 0, -1,  1,  1, -1,  0])