Data Science & Machine Learning
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A-Z of Data Science Part-2
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Master Power BI with this Cheat Sheet๐Ÿ”ฅ

If you're preparing for a Power BI interview, this cheat sheet covers the key concepts and DAX commands you'll need. Bookmark it for last-minute revision!

๐Ÿ“ ๐—ฃ๐—ผ๐˜„๐—ฒ๐—ฟ ๐—•๐—œ ๐—•๐—ฎ๐˜€๐—ถ๐—ฐ๐˜€:

DAX Functions:

- SUMX: Sum of values based on a condition.
- FILTER: Filter data based on a given condition.
- RELATED: Retrieve a related column from another table.
- CALCULATE: Perform dynamic calculations.
- EARLIER: Access a column from a higher context.
- CROSSJOIN: Create a Cartesian product of two tables.
- UNION: Combine the results from multiple tables.
- RANKX: Rank data within a column.
- DISTINCT: Filter unique rows.

Data Modeling:

- Relationships: Create, manage, and modify relationships.
- Hierarchies: Build time-based hierarchies (e.g., Date, Month, Year).
- Calculated Columns: Create calculated columns to extend data.
- Measures: Write powerful measures to analyze data effectively.

Data Visualization:

- Charts: Bar charts, line charts, pie charts, and more.
- Table & Matrix: Display tabular data and matrix visuals.
- Slicers: Create interactive filters.
- Tooltips: Enhance visual interactivity with tooltips.
- Map: Display geographical data effectively.

โœจ ๐—˜๐˜€๐˜€๐—ฒ๐—ป๐˜๐—ถ๐—ฎ๐—น ๐—ฃ๐—ผ๐˜„๐—ฒ๐—ฟ ๐—•๐—œ ๐—ง๐—ถ๐—ฝ๐˜€:

โœ… Use DAX for efficient data analysis.

โœ… Optimize data models for performance.

โœ… Utilize drill-through and drill-down for deeper insights.

โœ… Leverage bookmarks for enhanced navigation.

โœ… Annotate your reports with comments for clarity.

Like this post if you need more content like this ๐Ÿ‘โค๏ธ
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Complete 3-months roadmap to learn Artificial Intelligence (AI) ๐Ÿ‘‡๐Ÿ‘‡

### Month 1: Fundamentals of AI and Python

Week 1: Introduction to AI
- Key Concepts: What is AI? Categories (Narrow AI, General AI, Super AI), Applications of AI.
- Reading: Research papers and articles on AI.
- Task: Watch introductory AI videos (e.g., Andrew Ng's "What is AI?" on Coursera).

Week 2: Python for AI
- Skills: Basics of Python programming (variables, loops, conditionals, functions, OOP).
- Resources: Python tutorials (W3Schools, Real Python).
- Task: Write simple Python scripts.

Week 3: Libraries for AI
- Key Libraries: NumPy, Pandas, Matplotlib, Scikit-learn.
- Task: Install libraries and practice data manipulation and visualization.
- Resources: Documentation and tutorials on these libraries.

Week 4: Linear Algebra and Probability
- Key Topics: Matrices, Vectors, Eigenvalues, Probability theory.
- Resources: Khan Academy (Linear Algebra), MIT OCW.
- Task: Solve basic linear algebra problems and write Python functions to implement them.

---

### Month 2: Core AI Techniques & Machine Learning

Week 5: Machine Learning Basics
- Key Concepts: Supervised, Unsupervised learning, Model evaluation metrics.
- Algorithms: Linear Regression, Logistic Regression.
- Task: Build basic models using Scikit-learn.
- Resources: Courseraโ€™s Machine Learning by Andrew Ng, Kaggle datasets.

Week 6: Decision Trees, Random Forests, and KNN
- Key Concepts: Decision Trees, Random Forests, K-Nearest Neighbors (KNN).
- Task: Implement these algorithms and analyze their performance.
- Resources: Hands-on Machine Learning with Scikit-learn.

Week 7: Neural Networks & Deep Learning
- Key Concepts: Artificial Neurons, Forward and Backpropagation, Activation Functions.
- Framework: TensorFlow, Keras.
- Task: Build a simple neural network for a classification problem.
- Resources: Fast.ai, Coursera Deep Learning Specialization by Andrew Ng.

Week 8: Convolutional Neural Networks (CNN)
- Key Concepts: Image classification, Convolution, Pooling.
- Task: Build a CNN using Keras/TensorFlow to classify images (e.g., CIFAR-10 dataset).
- Resources: CS231n Stanford Course, Fast.ai Computer Vision.

---

### Month 3: Advanced AI Techniques & Projects

Week 9: Natural Language Processing (NLP)
- Key Concepts: Tokenization, Embeddings, Sentiment Analysis.
- Task: Implement text classification using NLTK/Spacy or transformers.
- Resources: Hugging Face, Coursera NLP courses.

Week 10: Reinforcement Learning
- Key Concepts: Q-learning, Markov Decision Processes (MDP), Policy Gradients.
- Task: Solve a simple RL problem (e.g., OpenAI Gym).
- Resources: Sutton and Bartoโ€™s book on Reinforcement Learning, OpenAI Gym.

Week 11: AI Model Deployment
- Key Concepts: Model deployment using Flask/Streamlit, Model Serving.
- Task: Deploy a trained model using Flask API or Streamlit.
- Resources: Heroku deployment guides, Streamlit documentation.

Week 12: AI Capstone Project
- Task: Create a full-fledged AI project (e.g., Image recognition app, Sentiment analysis, or Chatbot).
- Presentation: Prepare and document your project.
- Goal: Deploy your AI model and share it on GitHub/Portfolio.

### Tools and Platforms:
- Python IDE: Jupyter, PyCharm, or VSCode.
- Datasets: Kaggle, UCI Machine Learning Repository.
- Version Control: GitHub or GitLab for managing code.

Free Books and Courses to Learn Artificial Intelligence๐Ÿ‘‡๐Ÿ‘‡

Introduction to AI for Business Free Course

Top Platforms for Building Data Science Portfolio


Artificial Intelligence: Foundations of Computational Agents Free Book

Learn Basics about AI Free Udemy Course

Amazing AI Reverse Image Search

By following this roadmap, youโ€™ll gain a strong understanding of AI concepts and practical skills in Python, machine learning, and neural networks.

Join @free4unow_backup for more free courses

ENJOY LEARNING ๐Ÿ‘๐Ÿ‘
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Data Science Interview Questions with Answers ๐Ÿ‘‡

Q1: How would you analyze time series data to forecast production rates for a manufacturing unit? 

Ans: I'd use tools like Prophet for time series forecasting. After decomposing the data to identify trends and seasonality, I'd build a model to forecast production rates.


Q2: Describe a situation where you had to design a data warehousing solution for large-scale manufacturing data. 

Ans: For a project with multiple manufacturing units, I designed a star schema with a central fact table and surrounding dimension tables to allow for efficient querying.

Q3: How would you use data to identify bottlenecks in a production line? 

Ans:  I'd analyze production metrics, time logs, and machine efficiency data to identify stages in the production line with delays or reduced output, pinpointing potential bottlenecks.

Q4: How do you ensure data accuracy and consistency in a manufacturing environment with multiple data sources?

Ans: I'd implement data validation checks, use standardized data collection protocols across units, and set up regular data reconciliation processes to ensure accuracy and consistency.
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๐—ฆ๐—ค๐—Ÿ ๐—๐—ผ๐—ถ๐—ป๐˜€ ๐—–๐—ต๐—ฒ๐—ฎ๐˜๐˜€๐—ต๐—ฒ๐—ฒ๐˜ - ๐—™๐˜‚๐—น๐—น๐˜† ๐—˜๐˜…๐—ฝ๐—น๐—ฎ๐—ถ๐—ป๐—ฒ๐—ฑ

๐—ช๐—ต๐˜† ๐—ท๐—ผ๐—ถ๐—ป๐˜€ ๐—บ๐—ฎ๐˜๐˜๐—ฒ๐—ฟ?
Joins let you combine data from multiple tables to extract meaningful insights.
Every serious data analyst or backend dev should master these.

Letโ€™s break them down with clarity:

๐—œ๐—ก๐—ก๐—˜๐—ฅ ๐—๐—ข๐—œ๐—ก
โ†’ Returns only the rows with matching keys in both tables
โ†’ Think of it as intersection
๐—˜๐˜…๐—ฎ๐—บ๐—ฝ๐—น๐—ฒ:
Customers who have placed at least one order

SELECT *
FROM Customers
INNER JOIN Orders
ON Customers.ID = Orders.CustomerID;

๐—Ÿ๐—˜๐—™๐—ง ๐—๐—ข๐—œ๐—ก (๐—ข๐—จ๐—ง๐—˜๐—ฅ)
โ†’ Returns all rows from the left table + matching rows from the right
โ†’ If no match, right side = NULL
๐—˜๐˜…๐—ฎ๐—บ๐—ฝ๐—น๐—ฒ:
List all customers, even if theyโ€™ve never ordered

SELECT *
FROM Customers
LEFT JOIN Orders
ON Customers.ID = Orders.CustomerID;

๐—ฅ๐—œ๐—š๐—›๐—ง ๐—๐—ข๐—œ๐—ก (๐—ข๐—จ๐—ง๐—˜๐—ฅ)
โ†’ Returns all rows from the right table + matching rows from the left
โ†’ Rarely used, but similar logic
๐—˜๐˜…๐—ฎ๐—บ๐—ฝ๐—น๐—ฒ:
All orders, even from unknown or deleted customers

SELECT *
FROM Customers
RIGHT JOIN Orders
ON Customers.ID = Orders.CustomerID;

๐—™๐—จ๐—Ÿ๐—Ÿ ๐—ข๐—จ๐—ง๐—˜๐—ฅ ๐—๐—ข๐—œ๐—ก
โ†’ Returns all records when thereโ€™s a match in either table
โ†’ Unmatched rows = NULLs
๐—˜๐˜…๐—ฎ๐—บ๐—ฝ๐—น๐—ฒ:
Show all customers and all orders, whether matched or not

SELECT *
FROM Customers
FULL OUTER JOIN Orders
ON Customers.ID = Orders.CustomerID;

๐—–๐—ฅ๐—ข๐—ฆ๐—ฆ ๐—๐—ข๐—œ๐—ก
โ†’ Returns Cartesian product (all combinations)
โ†’ Use with care. 1,000 x 1,000 rows = 1,000,000 results!
๐—˜๐˜…๐—ฎ๐—บ๐—ฝ๐—น๐—ฒ:
Show all possible product and supplier pairings

SELECT *
FROM Products
CROSS JOIN Suppliers;

๐—ฆ๐—˜๐—Ÿ๐—™ ๐—๐—ข๐—œ๐—ก
โ†’ Join a table to itself
โ†’ Used for hierarchical data like employees & managers
๐—˜๐˜…๐—ฎ๐—บ๐—ฝ๐—น๐—ฒ:
Find each employeeโ€™s manager

SELECT A.Name AS Employee, B.Name AS Manager
FROM Employees A
JOIN Employees B
ON A.ManagerID = B.ID;

๐—•๐—ฒ๐˜€๐˜ ๐—ฃ๐—ฟ๐—ฎ๐—ฐ๐˜๐—ถ๐—ฐ๐—ฒ๐˜€
โ†’ Always use aliases (A, B) to simplify joins
โ†’ Use JOIN ON instead of WHERE for better clarity
โ†’ Test each join with LIMIT first to avoid surprises

---
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Machine Learning Algorithm
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๐’๐๐‹ ๐‚๐š๐ฌ๐ž ๐’๐ญ๐ฎ๐๐ข๐ž๐ฌ ๐Ÿ๐จ๐ซ ๐ˆ๐ง๐ญ๐ž๐ซ๐ฏ๐ข๐ž๐ฐ:

Join for more: https://t.iss.one/sqlanalyst

1. Dannyโ€™s Diner:
Restaurant analytics to understand the customer orders pattern.
Link: https://8weeksqlchallenge.com/case-study-1/

2. Pizza Runner
Pizza shop analytics to optimize the efficiency of the operation
Link: https://8weeksqlchallenge.com/case-study-2/

3. Foodie Fie
Subscription-based food content platform
Link: https://lnkd.in/gzB39qAT

4. Data Bank: Thatโ€™s money
Analytics based on customer activities with the digital bank
Link: https://lnkd.in/gH8pKPyv

5. Data Mart: Fresh is Best
Analytics on Online supermarket
Link: https://lnkd.in/gC5bkcDf

6. Clique Bait: Attention capturing
Analytics on the seafood industry
Link: https://lnkd.in/ggP4JiYG

7. Balanced Tree: Clothing Company
Analytics on the sales performance of clothing store
Link: https://8weeksqlchallenge.com/case-study-7

8. Fresh segments: Extract maximum value
Analytics on online advertising
Link: https://8weeksqlchallenge.com/case-study-8
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Getting a job in 2017:

Apply, get interview, get offer, negotiate salary, start job.

Getting a job in 2025:

Find job you are overqualified for that is underpaying market rates, connect with current employees and ask for a recommendation, bake a cake for the potential team youโ€™ll be apart of and hope your efforts are better than other candidates, meet with the third cousin of the hiring manager to see if you are a good fit to maybe start the process of interviewing, take a 3-hour long pass
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Cold email template for Freshers ๐Ÿ‘‡

Dear {NAME},

I hope this email finds you in good health and high spirits. I am writing to express my keen interest in the internship opportunity at the {NAME} and to submit my application for your consideration.


Allow me to introduce myself. My name is Ashok Aggarwal, and I am a statistics major with a specialization in Data Science. I have been following the remarkable work conducted by {NAME} and the valuable contributions it has made to the field of biomedical research and public health. I am truly inspired by the {One USP}


Having reviewed the internship description and requirements, I firmly believe that my academic background and skills make me a strong candidate for this opportunity. I have a solid foundation in statistics and data analysis, along with proficiency in relevant software such as Python, NumPy, Pandas, and visualization tools like Matplotlib. Furthermore, my prior project on {xyz} has reinforced my passion for utilizing data-driven insights to understand {XYZ}


Joining {name} for this internship would provide me with a tremendous platform to contribute my statistical expertise and collaborate with esteemed scientists like yourself. I am eager to work closely with the research team, assist in communications campaigns, engage in community programs, and learn from the collective expertise at {Name}.


I have attached my resume and would be grateful if you could review my application. I am available for an interview at your convenience to further discuss my qualifications and how I can contribute to {NAME} initiatives. I genuinely appreciate your time and consideration.


Thank you for your attention to my application. I look forward to the possibility of joining {NAME} and making a meaningful contribution to the organization's mission. Should you require any further information or documentation, please do not hesitate to contact me.

Wishing you a productive day ahead.


Sincerely,

{Full Name}
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Data Science vs. Data Analytics
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Handling Datasets of All Types โ€“ Part 1 of 5: Introduction and Basic Concepts โ˜‘๏ธ


1. What is a Dataset?

โ€ข A dataset is a structured collection of data, usually organized in rows and columns, used for analysis or training machine learning models.

2. Types of Datasets

โ€ข Structured Data: Tables, spreadsheets with rows and columns (e.g., CSV, Excel).

โ€ข Unstructured Data: Images, text, audio, video.

โ€ข Semi-structured Data: JSON, XML files containing hierarchical data.

3. Common Dataset Formats

โ€ข CSV (Comma-Separated Values)

โ€ข Excel (.xls, .xlsx)

โ€ข JSON (JavaScript Object Notation)

โ€ข XML (eXtensible Markup Language)

โ€ข Images (JPEG, PNG, TIFF)

โ€ข Audio (WAV, MP3)


4. Loading Datasets in Python

โ€ข Use libraries like pandas for structured data:

import pandas as pd
df = pd.read_csv('data.csv')


โ€ข Use libraries like json for JSON files:

import json
with open('data.json') as f:
    data = json.load(f)



5. Basic Dataset Exploration

โ€ข Check shape and size:

print(df.shape)


โ€ข Preview data:

print(df.head())


โ€ข Check for missing values:

print(df.isnull().sum())



6. Summary

โ€ข Understanding dataset types is crucial before processing.

โ€ข Loading and exploring datasets helps identify cleaning and preprocessing needs.


Exercise

โ€ข Load a CSV and JSON dataset in Python, print their shapes, and identify missing values.

Hope this helped you โœ”๏ธ
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Convolutional Neural Network Cheat Sheet
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What's the correct answer ๐Ÿ‘‡๐Ÿ‘‡
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Data Science & Machine Learning
What's the correct answer ๐Ÿ‘‡๐Ÿ‘‡
a = "10" โ†’ Variable a is assigned the string "10".

b = a โ†’ Variable b also holds the string "10" (but it's not used afterward).

a = a * 2 โ†’ Since a is a string, multiplying it by an integer results in string repetition.

"10" * 2 results in "1010"

print(a) โ†’ prints the new value of a, which is "1010".


โœ… Correct answer: D. 1010
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๐Ÿ”ฐ Python Question / Quiz

What is the output of the following Python code?
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