CS - Grade XII - Random Module Notes

 

Random Module

The randrange() function in Python is used to generate a random number from a specified range. It is part of the random module. Here are a few examples to demonstrate how it works.

import random

# Random number from 0 to 9

num = random.randrange(10)

print(num)  # Output: Any number from 0 to 9

 

# Random number from 5 to 14

num = random.randrange(5, 15)

print(num)  # Output: Any number from 5 to 14

 

# Random even number from 0 to 18

num = random.randrange(0, 20, 2)

print(num)  # Output: 0, 2, 4, ..., 18

 

for i in range(5):

    print(random.randrange(1, 100))

# Output: 5 random numbers between 1 and 99

 import random

#EG:

fruits = ['apple', 'banana', 'cherry', 'date', 'fig']

# Get a random index within the list

index = random.randrange(len(fruits))

# Access the list using the random index

print("Random fruit:", fruits[index])

The random() function in Python is used to generate a random floating-point number between 0.0 and 1.0 (not including 1.0). It is also part of the random module.

import random

num = random.random()

print(num)  # Output: Random float between 0.0 and 1.0

 

# Random float between 0 and 10

num = random.random() * 10

print(num)

Example:

If random.random() gives 0.6345, then:

$0.6345 \times 10 = 6.345$

 

 # Random float between 5 and 10

num = 5 + (random.random() * 5)

print(num)

 

for i in range(3):

    print(random.random())

# Output: 3 random floats between 0.0 and 1.0

 

The randint() function in Python is used to generate a random integer between two specified values inclusive (meaning both end values are included).

It’s part of the random module

 

import random

num = random.randint(1, 10)

print(num)  # Output: Random integer from 1 to 10 (inclusive)

 

dice = random.randint(1, 6)

print("Dice roll:", dice)  # Output: 1 to 6

 

student_roll = random.randint(1001, 1020)

print("Random roll number:", student_roll)

 

neg_num = random.randint(-10, -1)

print("Random negative number:", neg_num)  # Output: between -10 and -1

 

for _ in range(5):

    print(random.randint(10, 20))

# Output: 5 random integers between 10 and 20

 

Q1. Write a random number generator that generates random numbers between 1 and 6 (simulates a dice).

import random

def roll_dice():

   print(random.randint(1, 6)) 

print("""Welcome to my python random dice program!

To start press enter! Whenever you are over, type quit.""")

flag = True

while flag:

   user_prompt = input(">")

   if user_prompt.lower() == "quit":

      flag = False

   else:

     print("Rolling dice...\nYour number is:") 

     roll_dice()

CBSE BOARD NOTES

Python Modules

Importing and using built-in modules — math, random, statistics

1. Importing Modules

 A module is a file containing Python definitions and functions. Use the import statement to load a module.

 Method 1 — import statement

Imports the entire module. Access functions using module.function() syntax.

import math

import random

import statistics

 

result = math.sqrt(25)   # must prefix with module name

 

Method 2 — from … import statement

Imports specific items directly. No prefix needed when calling.

from math import sqrt, pi

from random import randint

 

result = sqrt(25)   # no prefix needed

print(pi)           # 3.141592653589793

 

Method 3 — import all (use with caution)

from math import *   # imports everything from math

print(floor(3.7))    # 3

 

Note: Avoid using 'import *' in large programs — it can cause name conflicts when two modules have functions with the same name.

 

2. The math Module

The math module provides mathematical functions and constants. It is part of Python's standard library.

 Constants

Constant	Value	Description
math.pi	3.141592653589793	The mathematical constant pi (π)
math.e	2.718281828459045	Euler's number (base of natural log)

Functions

Function	Returns	Description
sqrt(x)	float	Square root of x
ceil(x)	int	Smallest integer ≥ x (rounds up)
floor(x)	int	Largest integer ≤ x (rounds down)
pow(x, y)	float	x raised to the power y
fabs(x)	float	Absolute value of x (always float)
sin(x)	float	Sine of x (x in radians)
cos(x)	float	Cosine of x (x in radians)
tan(x)	float	Tangent of x (x in radians)

 Examples

import math

 

print(math.sqrt(49))        # --> 7.0

print(math.ceil(4.2))        # --> 5

print(math.floor(4.9))       # --> 4

print(math.pow(2, 10))       # --> 1024.0

print(math.fabs(-7.5))       # --> 7.5

print(math.sin(math.pi/2))   # --> 1.0

print(math.cos(0))           # --> 1.0

print(math.tan(math.pi/4))   # --> ~1.0

3. The random Module

The random module generates pseudo-random numbers. Results change each time the program runs.

Functions

Function	Returns	Description
random()	float	Random float in [0.0, 1.0) — includes 0, excludes 1
randint(a, b)	int	Random integer from a to b (both inclusive)
randrange(start, stop)	int	Random integer from start up to (not including) stop
randrange(start,stop,step)	int	Random integer from range with given step

 Examples

import random

print(random.random())            # --> e.g. 0.5731  (changes each run)

print(random.randint(1, 6))       # --> 1 to 6  (like rolling a die)

print(random.randrange(0, 10, 2)) # --> 0, 2, 4, 6, or 8

Note: Key difference: randint(1, 6) includes both 1 and 6. randrange(1, 6) gives 1 to 5 only — 6 is excluded.

 

4. The statistics Module

The statistics module provides functions for calculating basic statistical measures on numeric data.

Functions

Function	Returns	Description
mean(data)	float	Arithmetic average of all values
median(data)	float/int	Middle value when data is sorted
mode(data)	value	The most frequently occurring value

Examples

import statistics

data = [4, 7, 2, 9, 7, 5, 3]

print(statistics.mean(data))    # --> 5.285714...

print(statistics.median(data))  # --> 5   (sorted: 2,3,4,5,7,7,9)

print(statistics.mode(data))    # --> 7   (appears most often)

 

Note: mode() raises StatisticsError if no single value appears most often (Python < 3.8). In Python 3.8+, it returns the first mode found.

 

Quick Reference Summary

Module	Import	Key Items
math	import math	pi, e, sqrt, ceil, floor, pow, fabs, sin, cos, tan
random	import random	random(), randint(a,b), randrange(start,stop,step)
statistics	import statistics	mean(data), median(data), mode(data)

 

 

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