numpy

Question 1

create a 1 rank numpy array with elements 1, 2, 3

Answer 1

a = np.array([1, 2, 3])

Question 2

read the output of this:
a = np.array([1, 2, 3])

a.shape

Answer 2

prints (3,). total rows by columns

Question 3

How do you select an element from a 1 rank array?

a = np.array([1, 2, 3])

Answer 3

Using brackets: a[0], a[1], a[3]

Question 4

how would create a rank 2 array?

Answer 4

specify it as a list of list

a = np.array([1,2,3], [4, 5, 6])

Question 5

how would you access an element from a rank 2 array?

a = np.array([1,2,3], [4, 5, 6])

Answer 5

a = np.array([1,2,3], [4, 5, 6])

a[0, 0] // prints 1
a[1, 1] // prints 5

Question 6

How would you create an empty array of all zeros?

Answer 6

for 1 rank array

a = np.zeros((3, 1))

for 2 rank array

a = np.zeros(3, 2))

Question 7

What’s a rank 1 array?

Answer 7

an array with one axis: for example [1, 2, 1] is a rank of 1. the axis length = 3

Question 8

what’s a rank 2 array?

Answer 8

must have two axis.

[[1, 0, 1],
[0, 1, 2]]