How to create a random list of numbers in python

There is a need to generate random numbers when studying a model or behavior of a program for different range of values. Python can generate such random numbers by using the random module. In the below examples we will first see how to generate a single random number and then extend it to generate a list of random numbers.

Generating a Single Random Number

The random[] method in random module generates a float number between 0 and 1.

Example

import random
n = random.random[]
print[n]

Output

Running the above code gives us the following result −

0.2112200

Generating Number in a Range

The randint[] method generates a integer between a given range of numbers.

Example

import random
n = random.randint[0,22]
print[n]

Output

Running the above code gives us the following result −

2

Generating a List of numbers Using For Loop

We can use the above randint[] method along with a for loop to generate a list of numbers. We first create an empty list and then append the random numbers generated to the empty list one by one.

Example

import random
randomlist = []
for i in range[0,5]:
n = random.randint[1,30]
randomlist.append[n]
print[randomlist]

Output

Running the above code gives us the following result −

[10, 5, 21, 1, 17]

Using random.sample[]

We can also use the sample[] method available in random module to directly generate a list of random numbers.Here we specify a range and give how many random numbers we need to generate.

Example

import random
#Generate 5 random numbers between 10 and 30
randomlist = random.sample[range[10, 30], 5]
print[randomlist]

Output

Running the above code gives us the following result −

[16, 19, 13, 18, 15]

Updated on 08-Aug-2019 06:54:57

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Sometimes, in making programs for gaming or gambling, we come across the task of creating a list all with random numbers in Python. This task is to perform in general using loop and appending the random numbers one by one. But there is always a requirement to perform this in the most concise manner. Let’s discuss certain ways in which this can be done.

Random Number Using random module

Python Random module is an in-built module of Python which is used to generate random numbers. This module can be used to perform random actions such as generating random numbers, printing random a value for a list or string, etc.

Method 1: Using the random.randint[]

By using random.randint[] we can add random numbers into a list.

Python3

import random

rand_list=[]

n=10

for i in range[n]:

    rand_list.append[random.randint[3,9]]

print[rand_list]

Output

[9, 3, 3, 6, 8, 5, 4, 6, 3, 7]

Method 2: Using random.sample[] 

This single utility function performs the exact required as asked by the problem statement, it generated N no. of random numbers in a list in the specified range and returns the required list.

Python3

import random

res = random.sample[range[1, 50], 7]

print ["Random number list is : " +  str[res]]

Output

Random number list is : [49, 20, 23, 34, 6, 29, 35]

Method 3: Using list comprehension + randrange[] 

The naive method to perform this particular task can be shortened using list comprehension. randrange function is used to perform the task of generating the random numbers. 

Python3

import random

res = [random.randrange[1, 50, 1] for i in range[7]]

print ["Random number list is : " +  str[res]]

Output

Random number list is : [32, 16, 9, 28, 19, 31, 21]

Method 4: using loop + randint[]

Python3

import random

lis = []

for _ in range[10]:

    lis.append[random.randint[0, 51]]

print[lis]

Output:

[3, 11, 48, 2, 48, 2, 8, 51, 8, 5]

Random Number Using Numpy

The random function provided by the Numpy module can be more useful for you as it provides little better functionality and performance as compared to the random module.

Method 1: Generating a list of random integers using numpy.random.randint function

This function returns random integers from the “discrete uniform” distribution of the integer data type.

Python3

import numpy as np

print[list[np.random.randint[low = 3,high=8,size=10]]]

print[list[np.random.randint[low = 3,size=5]]]

Output: 
[5, 3, 6, 7, 4, 5, 7, 7, 7, 7]
[0, 2, 1, 2, 1]

Method 2. Generating a list of random floating values using numpy.random.random_sample function

This function return random float values in half open interval [0.0, 1.0].

Python3

import numpy as np

print[np.random.random_sample[size = 4]]

print[np.random.random_sample[size = [4,4]]]

output:
[0.08035145 0.94966245 0.92860366 0.22102797]
[[0.02937499 0.50073572 0.58278742 0.02577903]
 [0.37892104 0.60267882 0.33774815 0.28425059]
 [0.57086088 0.07445422 0.86236614 0.33505317]
 [0.83514508 0.82818536 0.1917555  0.76293027]]

The benefit of using numpy.random over the random module of Python is that it provides a few extra probability distributions which can help in scientific research.

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