# Random Module in Python Class 11-12 Notes

Random numbers are widely used in programs which involves games or simulations. Some uses of random numbers are as follows:

♦ To shuffle a deck of playing cards randomly

♦ To play a game of chances where the computer needs to throw some dice, pick a number randomly or flip a coin.

♦ Generation of captcha

♦ Random selection of winner in lucky draw contest.

### How to use random module?

To use random module, firstly you should import random at the beginning of your code.

### import random

There are many functions such as random(), randrange(), randint(), shuffle(), uniform(), and choice() in random module. Here we learn the working of these functions.

### 1. random( )

This function generates random numbers between 0 and 1. It means the result will be between 0 or less than 1 (including 0, but excluding 1). It will never give 1 as output means output may be 0, 0.123,0.9999 etc. It will generate different number on each execution. This function can be used to generate pseudorandom * floating point* values.

Example:

import random random_number=random.random() print(random_number)

**Output:**

First Run:

`0.319979864671`

Second Run:

`0.582918157917`

Third Run:

`0.55455335024`

Fourth Run:

`0.547415686776`

### 2. randrange()

This function generate random integer numbers between ranges (lower and upper argument).

**Ex 1: random_number=random.randrange(10)**

The above code will generate random number between 0 to 9. (as we know indexing)

import random random_number=random.randrange(10) print(random_number)

Output:

First Run:

`3`

Second Run:

`7`

Third Run:

`6`

**Ex 2: random_number=random.randrange(10,21)**

The above code will generate random number between 10 to 20. (as we know indexing)

import random random_number=random.randrange(10,21) print(random_number)

Output:

First Run:

`11`

Second Run:

`18`

Third Run:

`16`

**Ex 3: random_number=random.randrange(10,20,3)**

The above code will generate random number between 10 to 19 with step 3. (as we know indexing)

### 3. randint ()

This function returns a random integer between a given start and stop integer.

Parameters: It takes two parameters. Both are mandatory.

start: It is the start position of a range. The default value is 0 if not specified.

stop: It is the end position of a range.

**Syntax:**

**random.randint(start,stop)**

**Example:**

import random random_number=random.randint(10,20) print(random_number)

**Output:**

First Run:

`18`

### 4. uniform()

Returns a random floating point number between 2 numbers.

Syntax:

random.uniform(a,b)

Here a is lower limit and b is the upper limit of the random float. The returned random float may be equal or greater than a and less than b.

Example:

import random random_number=random.uniform(10,20) print(random_number)

Output:

`12.0785116829`

### 5. choice()

Used for making a random selection from a sequence (list,tuple,string)

Syntax:

random.choice(sequence)

Example:

import random my_choice=random.choice(["RED","YELLOW","GREEN", "BLUE"]) print(my_choice)

Output:

First Run:

`BLUE`

Second Run:

`YELLOW`

Third Run:

`GREEN`

### 6. shuffle()

Used to shuffle the contents in a sequence (list).

Syntax:

shuffle(list)

Example:

import random color=["RED","YELLOW","GREEN", "BLUE"] random.shuffle(color) print(color)

Output:

First Run:

`['RED', 'GREEN', 'YELLOW', 'BLUE']`

Second Run:

`['GREEN', 'RED', 'YELLOW', 'BLUE']`

Third Run:

`['BLUE', 'YELLOW', 'RED', 'GREEN']`

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