numpy basics

Question 1

Import NumPy as np

Answer 1

import numpy as np

Question 2

Create an array of 10 zeros

Answer 2

zero_array = np.zeros(10)
zero_array

Question 3

Create an array of 10 ones

Answer 3

ones_array = np.ones(10)
ones_array

Question 4

Create an array of 10 fives

Answer 4

fives_array = 5*(np.ones(10))
fives_array

Question 5

Create an array of the integers from 10 to 50

Answer 5

ten_fifty_array = np.arange(10,51)
ten_fifty_array

Question 6

Create an array of all the even integers from 10 to 50

Answer 6

ten_fifty_even = np.arange(10,51,2)
ten_fifty_even

Question 7

Create a 3x3 matrix with values ranging from 0 to 8

Answer 7

matrix1 = np.arange(0,9).reshape(3,3)
matrix1

Question 8

Create a 3x3 identity matrix

Answer 8

ident = np.eye(3)
ident

Question 9

Use NumPy to generate a random number between 0 and 1

Answer 9

num_1_to_2 = np.random.rand(1)
num_1_to_2

Question 10

Use NumPy to generate an array of 25 random numbers sampled from a standard normal distribution

Answer 10

random25_normal = np.random.randn(25)
random25_normal

Question 11

Create the following matrix:

Answer 11

matrix2 = (np.arange(1,101).reshape(10,10))/100
matrix2

Question 12

Create an array of 20 linearly spaced points between 0 and 1:

Answer 12

array20 = np.linspace(0,1,20)
array20

Question 13

mat = np.arange(1,26).reshape(5,5)
mat

give me the subset of this

Answer 13

mat[2:5,1:5]

Question 14

mat = np.arange(1,26).reshape(5,5)
mat

give me the subset of this

20

Answer 14

mat[3:4,-1]

Question 15

mat = np.arange(1,26).reshape(5,5)
mat

give me the subset of this

array([[2],

[7],

[12]])

Answer 15

mat[0:3,1:2]

Question 16

mat = np.arange(1,26).reshape(5,5)
mat

give me the subset of this

‘array([21, 22, 23, 24, 25])’

Answer 16

mat[-1,0:5]

Question 17

mat = np.arange(1,26).reshape(5,5)
mat

give me the subset of this

” array([[16, 17, 18, 19, 20],

[21, 22, 23, 24, 25]]) “

Answer 17

mat[3:5,0:5]

Question 18

mat = np.arange(1,26).reshape(5,5)
mat

Get the sum of all the values in mat

Answer 18

np.sum(mat)

Question 19

mat = np.arange(1,26).reshape(5,5)
mat

find the stanard dev of the matrix numbers

Answer 19

np.std(mat)

Question 20

mat = np.arange(1,26).reshape(5,5)
mat

add all colums

Answer 20

np.sum(mat,axis = 0)