What are random numbers?
Random numbers don't mean different numbers every time. Random means something that cannot be predicted logically.
pseudo random and true random
Computers work on programs, which are authoritative sets of instructions. So this means there must be some kind of algorithm to generate random numbers.
If there is a program that generates random numbers, it can be predicted, so it is not truly random.
Random numbers generated by a generative algorithm are called pseudo-random numbers.
Can we generate truly random numbers?
Yes. In order to generate a truly random number on our computer, we need to get random data from some external source. External sources are usually our keystrokes, mouse movements, network data, etc.
We don't need truly random numbers unless it's related to security (eg encryption keys) or the basis of the application is randomness (eg digital roulette wheel).
In this tutorial, we will use pseudorandom numbers.
Generate random numbers
NumPy provides the random module to handle random numbers.
example
Generate a random integer between 0 and 100:
from numpy import random
x = random.randint(100)
print(x)
run instance
generate random floating point
The rand() method of the random module returns a random floating point number between 0 and 1.
example
Generate a random floating point number between 0 and 100:
from numpy import random
x = random.rand()
print(x)
run instance
generate random array
In NumPy, we can use the two methods in the above example to create random arrays.
The integer
randint() method accepts a size parameter where you can specify the shape of the array.
example
Generate a 1-D array of 5 random integers from 0 to 100:
from numpy import random
x=random.randint(100, size=(5))
print(x)
run instance
example
Generate a 2-D array with 3 rows, each containing 5 random integers from 0 to 100:
from numpy import random
x = random.randint(100, size=(3, 5))
print(x)
run instance
floating point number
The rand() method also allows you to specify the shape of the array.
example
Generate a 1-D array of 5 random floating-point numbers:
from numpy import random
x = random.rand(5)
print(x)
run instance
example
Generate a 2-D array with 3 rows, each containing 5 random numbers:
from numpy import random
x = random.rand(3, 5)
print(x)
run instance
Generate random numbers from an array
The choice() method allows you to generate random values based on an array of values.
The choice() method takes an array as a parameter and returns one of the values at random.
example
Return one of the values in the array:
from numpy import random
x = random.choice([3, 5, 7, 9])
print(x)
run instance
The choice() method also allows you to return an array of values.
Please add a size parameter to specify the shape of the array.
example
Generate a two-dimensional array of the values in the array arguments (3, 5, 7, and 9):
from numpy import random
x = random.choice([3, 5, 7, 9], size=(3, 5))
print(x)
run instance
