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Advanced Python Concepts

Jun 21, 2024

Lecture Notes: Advanced Python Concepts

1. Virtual Environments

  • Purpose: Isolate dependencies for different Python projects to avoid conflicts.
  • Commands:
    • Create: virtualenv env_name
    • Activate (Windows): env_name\Scripts\activate.ps1
    • Deactivate: deactivate
  • Example: Create multiple environments (env1, env2) and install different packages (pandas, pyjokes), then freeze dependencies to requirements.txt with pip freeze > requirements.txt and install with pip install -r requirements.txt.

2. Lambda Functions

  • Syntax: lambda arguments: expression
  • Example: square = lambda n: n * n for squaring a number.
  • Usage: Quick function definitions for simple operations.*

3. The Join Method

  • Purpose: Concatenate elements in a list with a specified separator.
  • Syntax: separator.join(iterable)
  • Example: '-'.join(['Harry', 'Rohan', 'Shubham']) → Harry-Rohan-Shubham.

4. The Format Method

  • Purpose: Insert variables into strings at specified places.
  • Syntax: {} for position-based formatting.
  • Example: ",".format(name, marks, phone)

5. Map, Filter, and Reduce

Map

  • Usage: Apply a function to all items in an input list.
  • Syntax: map(function, iterable)
  • Example: Squaring numbers in a list map(lambda x: x*x, [1, 2, 3, 4])*

Filter

  • Usage: Filter items out of a list.
  • Syntax: filter(function, iterable)
  • Example: Filter even numbers filter(lambda x: x % 2 == 0, [1, 2, 3, 4])

Reduce

  • Usage: Apply a rolling computation to sequential pairs of values in a list.
  • Syntax: reduce(function, iterable) from functools
  • Example: Calculate sum reduce(lambda x, y: x + y, [1, 2, 3, 4])

6. Error Handling with Try, Except, Else, and Finally

  • Purpose: Manage errors gracefully and perform clean-up operations.
  • Syntax: try: # code that might raise an exception except SomeException as e: # code that runs if an exception occurs else: # code that runs if no exception occurs finally: # code that always runs (clean-up code)
  • Example: Handle division by zero and other errors efficiently.

7. Name Equals Main

  • Purpose: Ensure that certain code runs only when a module is executed directly, not when imported.
  • Syntax: if __name__ == "__main__":
  • Example: if __name__ == "__main__": main()
  • Usage: Helps in debugging and code reusability.

8. Global Keyword

  • Purpose: Modify a global variable inside a function.
  • Syntax: global var_name
  • Example: a = 10 def update(): global a a = 20 update() print(a) # 20
  • Usage: Change global variables within functions.

9. List Comprehension

  • Purpose: Compact and readable way of creating lists.
  • Syntax: [expression for item in iterable]
  • Example: Squaring numbers [x*x for x in range(10)]
  • Usage: Efficient and readable list generation.*

10. Advanced Python Functions (Merging Dictionaries, Multiple Context Managers, etc.)

  • Merging Dictionaries: Use ** unpacking to merge.
  • Context Management: Efficiently handle multiple resources with with
  • Example: Merging dictionaries dict1 = {'a': 1} dict2 = {'b': 2} merged_dict = {**dict1, **dict2}
  • Multiple Context Managers: Unpack and manage multiple resources with open('file1.txt') as f1, open('file2.txt') as f2: ...

I hope these notes help you in effectively understanding and using advanced Python concepts!

Practice Set Solutions

Problem 1

Objective: Create virtual environments, install packages, and utilize requirements.txt

Commands:

pip install virtualenv virtualenv env1 source env1/bin/activate # For Unix-based systems .env1\Scripts\activate.ps1 # For Windows pip install pandas pyjokes pip freeze > requirements.txt pip install -r requirements.txt

Problem 2

Objective: Format a string using the format method

name = input('Enter name: ') marks = int(input('Enter marks: ')) phone = input('Enter phone number: ') formatted_string = "Name: {}, Marks: {}, Phone: {}".format(name, marks, phone) print(formatted_string)

Problem 3

Objective: Use the join method to concatenate elements of a list with a separator

table = [7 * i for i in range(1, 11)] sequence = '\n'.join(map(str, table)) print(sequence)

Problem 4

Objective: Filter list of numbers that are divisible by 5

def divisible_by_5(x): return x % 5 == 0 l = [1, 2, 10, 3, 15, 25] filtered_list = list(filter(divisible_by_5, l)) print(filtered_list)

Problem 5

Objective: Use reduce to find the maximum number in a list

from functools import reduce def max_reduce(a, b): return a if a > b else b numbers = [1, 2, 5, 6, 3] max_number = reduce(max_reduce, numbers) print(f'The maximum number is: {max_number}')

Problem 6

Objective: Use pip freeze to export and recreate environment

Commands:

pip freeze > requirements.txt pip install -r requirements.txt

Problem 7

Objective: Create a simple web server using Flask

from flask import Flask app = Flask(__name__) @app.route("/") def hello(): return "Hello, World!" if __name__ == "__main__": app.run()

I hope these practice sets help you in applying advanced Python concepts efficiently! 😊

😎 Have a great time coding!

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Happy Learning!

Source: Lecture/Presentation on Advanced Python Concepts.

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