Concept of Library and Packages in Python - 10

1. Library

Definition

A library is a collection of pre-written modules that provide useful functions and tools to perform different tasks without writing the code from scratch. Python provides many built-in libraries, and programmers can also install additional libraries for specialized tasks.

Examples of Popular Python Libraries

TensorFlow

TensorFlow is an open-source Python library developed by Google for Artificial Intelligence (AI) and Machine Learning (ML). It is mainly used to create and train intelligent computer programs.

Matplotlib

Matplotlib is a Python library used to create graphs, charts, and data visualizations. It helps represent data in an easy-to-understand graphical form.

Pandas

Pandas is a Python library used for data analysis and data manipulation. It provides powerful tools to organize, clean, and process large sets of data efficiently.

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2. Module

Definition

A module is a single Python file (.py) that contains functions, variables, and classes related to a specific purpose. Modules help organize programs into smaller and reusable parts.

Examples

• math
• random
• os
• calendar

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3. Package

Definition

A package is a collection of related modules stored inside a folder. It helps organize multiple modules into a structured hierarchy. Packages make large Python programs easier to manage and maintain.

Example

The NumPy package contains many modules for mathematical and numerical operations.

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Importing and Using Standard Libraries

Introduction

Python provides many standard libraries that are already included with Python. These libraries contain useful modules and functions that help programmers perform common tasks such as mathematical calculations, generating random numbers, working with dates, handling files, and more.

To use a module from the standard library, it must first be imported into the program.

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1. Importing an Entire Library Module

Explanation

The import keyword is used to import the entire module. After importing, the module name must be written before using its functions.

Syntax

    import module_name
    

Example

    import math

    print(math.sqrt(25))
    print(math.factorial(5))
    

Output

    5.0
    120
    

Explanation

Here, the entire math module is imported. The functions sqrt() and factorial() are accessed using math. before their names.

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2. Importing Specific Functions or Items from a Module

Explanation

Instead of importing the whole module, only the required functions or variables can be imported. This allows the functions to be used directly without writing the module name.

Syntax

    from module_name import function_name
    

Example

    from math import sqrt, factorial

    print(sqrt(36))
    print(factorial(4))
    

Output

    6.0
    24
    

Explanation

Only the sqrt() and factorial() functions are imported from the math module, so they can be used directly without writing math..

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3. Importing Modules with Aliases

Explanation

A module can be imported with a shorter or custom name using the as keyword. This makes the code shorter and easier to write.

Syntax

    import module_name as alias_name
    

Example

    import math as m

    print(m.sqrt(49))
    print(m.pi)
    

Output

    7.0
    3.141592653589793
    

Explanation

The math module is imported with the alias m. All functions and variables are accessed using m instead of math.

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4. Importing Everything from a Module

Explanation

The * symbol imports all public functions, variables, and classes from a module. After importing, they can be used directly without the module name.

Syntax

    from module_name import *
    

Example

    from math import *

    print(sqrt(64))
    print(factorial(6))
    print(pi)
    

Output

    8.0
    720
    3.141592653589793
    

Explanation

All functions and constants from the math module are imported. Therefore, sqrt(), factorial(), and pi can be used directly without writing math..

Note

Although from module_name import * is allowed, it is generally not recommended in large programs because it may cause name conflicts and make the code less readable.

Math Module

Introduction

The Math Module is a built-in Python module that provides various mathematical functions and constants. It is commonly used to perform complex mathematical calculations such as finding square roots, factorials, powers, greatest common divisors, and more.

Before using the functions of the math module, it must be imported using the import statement.

    import math
    

Common Functions of the Math Module

Function	Description
ceil(x)	Returns the smallest integer greater than or equal to the given number.
fabs(x)	Returns the absolute (positive) value of a number.
factorial(x)	Returns the factorial of a positive integer.
gcd(a, b)	Returns the Greatest Common Divisor (GCD) of two numbers.
fmod(x, y)	Returns the remainder when x is divided by y.
pow(x, y)	Returns x raised to the power of y.
sqrt(x)	Returns the square root of a number.

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Random Module

Introduction

The Random Module is a built-in Python module used to generate random numbers and make random selections. It is useful in games, simulations, password generation, and many other applications.

Before using the random module, it must be imported.

    import random
    

Common Functions of the Random Module

Function	Description
seed()	Initializes the random number generator with a specific value.
randrange()	Returns a random number from a specified range.
randint()	Returns a random integer between two specified numbers (inclusive).
choice()	Returns a randomly selected element from a sequence such as a list or tuple.
choices()	Returns a list of randomly selected elements from a sequence.
sample()	Returns a specified number of unique random elements from a sequence.
random()	Returns a random floating-point number between 0.0 and 1.0.
shuffle()	Randomly rearranges the elements of a list.

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Matplotlib Module

Introduction

Matplotlib is a popular Python library used for creating graphs, charts, and other data visualizations. It helps present data in a clear and graphical format, making it easier to understand patterns and trends.

The most commonly used module in Matplotlib is pyplot, which provides functions for creating different types of charts.

    import matplotlib.pyplot as plt
    

Sample Math functions in Python usage

    from math import *
    
    print("Ceiling value of 1.3:", ceil(1.3))
    print("Absolute value of -3.5:", fabs(-3.5))
    print("Factorial of 5:", factorial(5))
    print("HCF of 4 and 6 is:", gcd(4,6))
    print("Remainder when 6 is divided by 4 is:", fmod(6,4))
    print("4 to the power of 3.5 is:", pow(4,3.5))
    print("Square root of 10 is:", sqrt(10))
    

Output:

    Ceiling value of 1.3: 2
    Absolute value of -3.5: 3.5
    Factorial of 5: 120
    HCF of 4 and 6 is: 2
    Remainder when 6 is divided by 4 is: 2.0
    4 to the power of 3.5 is: 128.0
    Square root of 10 is: 3.1622776601683795
    

Sample Random functions in Python usage

    import random

    random.seed(9)
    print(random.random())
    print(random.randrange(4,9))
    print(random.randint(4,9))
    print(random.choice([1,2,3,4,4,5,5,6,7,7,8]))
    print(random.choices([1,2,3,4,4,5,5,6,7,7,8]))
    print(random.sample([1,2,3,4,4,5,5,6,7,7,8],3))
    a_list=[1,2,3,4,4,5,5,6,7,7,8]
    random.shuffle(a_list)
    print(a_list)
    

Output:

    0.46300735781502145
    6
    6
    3
    [3]
    [8, 1, 5]
    [3, 8, 7, 4, 1, 5, 4, 5, 2, 6, 7]
    

Note: How is randrange different from randint function in random module?
Randrange works like a range in for loop in (start, stop condition, step value) pattern while Randint works in a listed for in [x,y] where both x and y points are included.

Book Exercise Solutions from Qn 1 to 8

    1# Calculate square root
    from math import sqrt
    n=int(input("Enter a number:"))
    print("Square root of ",n," is:",sqrt(n))

    2# Calculate factorial
    from math import factorial
    n=int(input("Enter a number:"))
    print("Factorial of ",n," is:",factorial(n))

    3# Calculate cosine 60
    from math import pi,cos
    print("Cosine of 60 degrees is:",cos(pi/3))

    4# Calculate power
    from math import pow
    base=int(input("Enter base value:"))
    power=int(input("Enter power value:"))
    print("Result:", pow(base,power))

    5# Generate randome integer from 1 to 50.
    from random import randint
    print(randint(1,50))

    6# Shuffle list of 10 integers
    from random import shuffle
    random_list=[1,4,3,2,6,5,8,7,9,8]
    shuffle(random_list)
    print(random_list)

    7# Guessing random number from 1-20.
    from random import randint
    correct=randint(1,20)
    result=True
    while result:
        guess=int(input("Enter guess(1-20):"))
        if guess==correct:
            print("Correct guess!")
            result=False
        else:
            print("Keep Guessing")

    8# Generate and store in list, 5 random numbers(1-50)
    from random import randint
    new_list=[]
    for i in range(5):
        generated_number=randint(1,50)
        new_list.append(generated_number)
    print(new_list)