Python Data Science Jobs & Interviews
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Your go-to hub for Python and Data Science—featuring questions, answers, quizzes, and interview tips to sharpen your skills and boost your career in the data-driven world.

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Professional Summary: File Handling in Python (Part 2 - Examples)

1. Reading an Entire File:
with open('data.txt', 'r') as f:
content = f.read()
print(content)


2. Reading Line by Line:
with open('data.txt', 'r') as f:
for line in f:
print(line.strip()) # strip() removes newline characters


3. Writing to a File (Overwrites):
with open('output.txt', 'w') as f:
f.write('Hello, World!\n')
f.write('This is a new line.')


4. Appending to a File:
with open('log.txt', 'a') as f:
f.write('New log entry\n')


5. Reading and Writing with `r+` mode:
with open('data.txt', 'r+') as f:
content = f.read()
f.seek(0) # Move pointer to beginning
f.write('New content at start\n' + content)


6. Handling JSON Files:
import json
# Writing JSON
data = {"name": "Alice", "age": 30}
with open('data.json', 'w') as f:
json.dump(data, f)

# Reading JSON
with open('data.json', 'r') as f:
loaded_data = json.load(f)
print(loaded_data['name']) # Output: Alice


7. Handling CSV Files:
import csv
# Writing CSV
with open('data.csv', 'w', newline='') as f:
writer = csv.writer(f)
writer.writerow(['Name', 'Age'])
writer.writerow(['Bob', 25])

# Reading CSV
with open('data.csv', 'r') as f:
reader = csv.reader(f)
for row in reader:
print(row) # Output: ['Name', 'Age'], then ['Bob', '25']



By: t.iss.one/DataScienceQ 🚀
1
30-Day Intensive Python Roadmap (4 Hours/Day)

Week 1: Core Fundamentals (Days 1-7)
* Day 1-2 (8h): Basic Syntax, Variables, Data Types, Operators.
* Day 3-4 (8h): Data Structures (Lists, Tuples, Sets, Dictionaries).
* Day 5 (4h): Control Flow (If, For, While loops).
* Day 6 (4h): Functions (def, lambda, *args, **kwargs).
* **Day 7 (4h):** Practice & Mini-Project (CLI Calculator, To-Do List).
* Checkpoint: You can solve basic algorithmic problems and build simple scripts.

Week 2: Intermediate Concepts (Days 8-14)
* Day 8-9 (8h): File I/O (Reading/Writing files, with statement).
* Day 10 (4h): Error Handling (Try/Except/Else/Finally).
* Day 11-12 (8h): Object-Oriented Programming (Classes, Objects, Inheritance).
* Day 13 (4h): Modules and Packages (import, pip, Virtual Environments).
* Day 14 (4h): Practice & Mini-Project (File Sorter, Basic OOP program).
* Checkpoint: You can structure code using OOP and handle external data files.

Week 3: Advanced Topics & Specialization (Days 15-23)
* Day 15 (4h): Decorators and Generators.
* Day 16 (4h): Iterators, __iter__, __next__.
* Day 17-18 (8h): Choose one:
* Web: Flask/Django basics (Routes, Templates).
* Data: NumPy & Pandas basics.
* Automation: Working with OS module, APIs (requests library).
* Day 19-20 (8h): Dive deeper into your chosen specialization.
* Day 21 (4h): Testing (Introduction to unittest or pytest).
* Day 22-23 (8h): Work on a larger project in your chosen track.
* Checkpoint: You can build a functional application in your chosen domain.

Week 4: Polishing & Deployment (Days 24-30)
* Day 24 (4h): Version Control with Git (Basics: add, commit, push).
* Day 25 (4h): Code Readability (PEP 8, writing clean code).
* Day 26-28 (12h): Final Project. Build something that uses all your skills.
* Day 29 (4h): Debugging techniques and logging.
* Day 30 (4h): Deploy your project (e.g., on GitHub, Heroku, PythonAnywhere).
* Final Checkpoint: You have a complete portfolio project and are ready for entry-level tasks.


By: t.iss.one/DataScienceQ 🚀
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==================================
🧠 By: https://t.iss.one/DataScienceM
1
Advanced Python Test

1. What is the output of the following code?
def func(x, l=[]):
for i in range(x):
l.append(i * i)
return l

print(func(2))
print(func(3, []))
print(func(3))

A) [0, 1] [0, 1, 4] [0, 1, 4]
B) [0, 1] [0, 1, 4] [0, 1, 4, 0, 1, 4]
C) [0, 1] [0, 1, 4] [0, 1, 4, 0, 1, 4, 0, 1, 4]
D) [0, 1] [0, 1, 4] [0, 1, 4, 0, 1, 4, 0, 1, 4, 0, 1, 4]

2. Which statement about metaclasses in Python is TRUE?
A) A metaclass is used to create class instances
B) The __call__ method of a metaclass controls instance creation
C) All classes must explicitly specify a metaclass
D) Metaclasses cannot inherit from other metaclasses

3. What does this decorator do?
from functools import wraps

def debug(func):
@wraps(func)
def wrapper(*args, **kwargs):
print(f"Calling {func.__name__}")
return func(*args, **kwargs)
return wrapper

A) Measures function execution time
B) Logs function calls with arguments
C) Prints the function name when called
D) Prevents function execution in debug mode

4. What is the purpose of context managers?
A) To manage class inheritance hierarchies
B) To handle resource allocation and cleanup
C) To create thread-safe operations
D) To optimize memory usage in loops

#Python #AdvancedPython #CodingTest #ProgrammingQuiz #PythonDeveloper #CodeChallenge


By: t.iss.one/DataScienceQ 🚀
3
Here are links to the most important free Python courses with a brief description of their value.


1. Coursera: Python for Everybody
Link: https://www.coursera.org/specializations/python
Importance: A perfect starting point for absolute beginners. Covers Python fundamentals and basic data structures, leading to web scraping and database access.

2. freeCodeCamp: Scientific Computing with Python
Link: https://www.freecodecamp.org/learn/scientific-computing-with-python/
Importance: Project-based certification. You build applications like a budget app or a time calculator, reinforcing learning through practical, portfolio-worthy projects.

3. Harvard's CS50P: CS50's Introduction to Programming with Python
Link: https://cs50.harvard.edu/python/2022/
Importance: A rigorous university-level course. Teaches core concepts and problem-solving skills with exceptional depth and clarity, preparing you for complex programming challenges.

4. Real Python Tutorials
Link: https://realpython.com/
Importance: An extensive resource for all levels. Offers in-depth articles, tutorials, and code examples on nearly every Python topic, from basics to advanced specialized libraries.

5. W3Schools Python Tutorial
Link: https://www.w3schools.com/python/
Importance: Excellent for quick reference and interactive learning. Allows you to read a concept and test code directly in the browser, ideal for fast learning and checking syntax.

6. Google's Python Class
Link: https://developers.google.com/edu/python
Importance: A concise, fast-paced course for those with some programming experience. Includes lecture videos and well-designed exercises to quickly get up to speed.

#Python #LearnPython #PythonProgramming #Coding #FreeCourses #PythonForBeginners #Developer #Programming


By: t.iss.one/DataScienceQ 🚀
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This channels is for Programmers, Coders, Software Engineers.

0️⃣ Python
1️⃣ Data Science
2️⃣ Machine Learning
3️⃣ Data Visualization
4️⃣ Artificial Intelligence
5️⃣ Data Analysis
6️⃣ Statistics
7️⃣ Deep Learning
8️⃣ programming Languages

https://t.iss.one/addlist/8_rRW2scgfRhOTc0

https://t.iss.one/Codeprogrammer
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Today I am 3️⃣0️⃣ years old, I am excited to make more successes and achievements

My previous year was full of exciting events and economic, political and programmatic noise, but I kept moving forward

Best regards
Eng. @HusseinSheikho 🔤
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🚀 What will be the output of this code?
soon
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This GitHub repository is a real treasure trove of free programming books.

Here you'll find hundreds of books on topics like #AI, #blockchain, app development, #game development, #Python #webdevelopment, #promptengineering, and many more

GitHub: https://github.com/EbookFoundation/free-programming-books

https://t.iss.one/CodeProgrammer
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Interview Question

What types of file objects are there?

Answer: In Python, file objects are abstractions that provide a unified interface for working with different data sources. They are divided into three types:

▶️Text (TextIO) — work with strings (str) and automatically encode/decode data. For example: open("file.txt", "r", encoding="utf-8").

▶️Binary (BufferedIO) — operate with bytes and are often used for images, videos, or arbitrary data. For example: open("image.jpg", "rb").

▶️Low-level (raw) (RawIO) — provide direct access to devices or files without buffering. Usually used inside the standard library, rarely applied directly.

All these types implement interfaces from io — io.TextIOBase, io.BufferedIOBase, and io.RawIOBase. The standard open() function under the hood returns the appropriate object depending on the mode.


tags: #interview

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Interview question

What is a hash table and where is it used in Python?

Answer: A hash table is a data structure that stores key–value pairs and provides fast access by key in time close to O(1).

In Python, the built-in dict and set structures are implemented based on hash tables:

▶️ Keys are hashed using __hash__() and compared via __eq__();

▶️ The hash code is used to compute the index in the array where the element is placed;

▶️ Starting from Python 3.6 (and guaranteed from 3.7), dict preserves the insertion order of keys thanks to the compact dict.

Important: the key must be hashable — that is, have an immutable hash and a consistent implementation of __hash__() and __eq__().


tags: #interview

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Interview question

Why is None a singleton object in Python?

Answer: None is the sole instance (singleton) of the NoneType, and all variables containing None refer to the same object. This saves memory because new instances are not created.

tags: #interview

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Interview Question

Why doesn't Python support method overloading the way Java or C++ do?

Answer: In Python, all methods are dynamic, and overloading based on their arguments (unlike statically typed languages where the method signature is considered).

Instead of overloading, Python offers:

▶️ Using default argument values

▶️ Using *args and **kwargs for flexible parameter acceptance

▶️ Using @staticmethod or @classmethod if variability is needed

▶️ Using singledispatch functions from functools for type-based handling

tags: #interview

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Interview question

Why are int and bool classes, and not "primitive types" as in other languages?

Answer: Because in Python everything is based on the object model. int, bool, str, and others are built-in classes, and each time you use them you create their instances. For example, 5 is an object of the int class.

Even the classes themselves, like int, are also objects. They are created using a special object called type, which is the default metaclass. Therefore, type(int) returns type.


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Python.pdf
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🏳️‍🌈 Notes "Mastering Python"
From Basic to Advanced

👨🏻‍💻 An excellent note that teaches everything from basic concepts to building professional projects with Python.

⭕️ Basic concepts like variables, data types, and control flow

Functions, modules, and writing reusable code

⭕️ Data structures like lists, dictionaries, sets, and tuples

Object-oriented programming: classes, inheritance, and polymorphism

⭕️ Working with files, error handling, and debugging

⬅️ Alongside, with practical projects like data analysis, web scraping, and working with APIs, you learn how to apply Python in the real world.

🌐 #Data_Science #DataScience
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