Data Science & Machine Learning
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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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How much Statistics must I know to become a Data Scientist?

This is one of the most common questions

Here are the must-know Statistics concepts every Data Scientist should know:

๐—ฃ๐—ฟ๐—ผ๐—ฏ๐—ฎ๐—ฏ๐—ถ๐—น๐—ถ๐˜๐˜†

โ†—๏ธ Bayes' Theorem & conditional probability
โ†—๏ธ Permutations & combinations
โ†—๏ธ Card & die roll problem-solving

๐——๐—ฒ๐˜€๐—ฐ๐—ฟ๐—ถ๐—ฝ๐˜๐—ถ๐˜ƒ๐—ฒ ๐˜€๐˜๐—ฎ๐˜๐—ถ๐˜€๐˜๐—ถ๐—ฐ๐˜€ & ๐—ฑ๐—ถ๐˜€๐˜๐—ฟ๐—ถ๐—ฏ๐˜‚๐˜๐—ถ๐—ผ๐—ป๐˜€

โ†—๏ธ Mean, median, mode
โ†—๏ธ Standard deviation and variance
โ†—๏ธ  Bernoulli's, Binomial, Normal, Uniform, Exponential distributions

๐—œ๐—ป๐—ณ๐—ฒ๐—ฟ๐—ฒ๐—ป๐˜๐—ถ๐—ฎ๐—น ๐˜€๐˜๐—ฎ๐˜๐—ถ๐˜€๐˜๐—ถ๐—ฐ๐˜€

โ†—๏ธ A/B experimentation
โ†—๏ธ T-test, Z-test, Chi-squared tests
โ†—๏ธ Type 1 & 2 errors
โ†—๏ธ Sampling techniques & biases
โ†—๏ธ Confidence intervals & p-values
โ†—๏ธ Central Limit Theorem
โ†—๏ธ Causal inference techniques

๐— ๐—ฎ๐—ฐ๐—ต๐—ถ๐—ป๐—ฒ ๐—น๐—ฒ๐—ฎ๐—ฟ๐—ป๐—ถ๐—ป๐—ด

โ†—๏ธ Logistic & Linear regression
โ†—๏ธ Decision trees & random forests
โ†—๏ธ Clustering models
โ†—๏ธ Feature engineering
โ†—๏ธ Feature selection methods
โ†—๏ธ Model testing & validation
โ†—๏ธ Time series analysis

Math & Statistics: https://whatsapp.com/channel/0029Vat3Dc4KAwEcfFbNnZ3O
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Random Module in Python ๐Ÿ‘†
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Data Scientist Roadmap ๐Ÿ“ˆ

๐Ÿ“‚ Python Basics
โˆŸ๐Ÿ“‚ Numpy & Pandas
โ€ƒโˆŸ๐Ÿ“‚ Data Cleaning
โ€ƒโ€ƒโˆŸ๐Ÿ“‚ Data Visualization (Seaborn, Plotly)
โ€ƒโ€ƒโ€ƒโˆŸ๐Ÿ“‚ Statistics & Probability
โ€ƒโ€ƒโ€ƒโ€ƒโˆŸ๐Ÿ“‚ Machine Learning (Sklearn)
โ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโˆŸ๐Ÿ“‚ Deep Learning (TensorFlow / PyTorch)
โ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโˆŸ๐Ÿ“‚ Model Deployment
โ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโˆŸ๐Ÿ“‚ Real-World Projects
โ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโ€ƒโˆŸโœ… Apply for Data Science Roles

React "โค๏ธ" For More
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SQL Basics for Beginners: Must-Know Concepts

1. What is SQL?
SQL (Structured Query Language) is a standard language used to communicate with databases. It allows you to query, update, and manage relational databases by writing simple or complex queries.

2. SQL Syntax
SQL is written using statements, which consist of keywords like SELECT, FROM, WHERE, etc., to perform operations on the data.
- SQL keywords are not case-sensitive, but it's common to write them in uppercase (e.g., SELECT, FROM).

3. SQL Data Types
Databases store data in different formats. The most common data types are:
- INT (Integer): For whole numbers.
- VARCHAR(n) or TEXT: For storing text data.
- DATE: For dates.
- DECIMAL: For precise decimal values, often used in financial calculations.

4. Basic SQL Queries
Here are some fundamental SQL operations:

- SELECT Statement: Used to retrieve data from a database.

     SELECT column1, column2 FROM table_name;

- WHERE Clause: Filters data based on conditions.

     SELECT * FROM table_name WHERE condition;

- ORDER BY: Sorts data in ascending (ASC) or descending (DESC) order.

     SELECT column1, column2 FROM table_name ORDER BY column1 ASC;

- LIMIT: Limits the number of rows returned.

     SELECT * FROM table_name LIMIT 5;

5. Filtering Data with WHERE Clause
The WHERE clause helps you filter data based on a condition:

   SELECT * FROM employees WHERE salary > 50000;

You can use comparison operators like:
- =: Equal to
- >: Greater than
- <: Less than
- LIKE: For pattern matching

6. Aggregating Data
SQL provides functions to summarize or aggregate data:
- COUNT(): Counts the number of rows.

     SELECT COUNT(*) FROM table_name;

- SUM(): Adds up values in a column.

     SELECT SUM(salary) FROM employees;

- AVG(): Calculates the average value.

     SELECT AVG(salary) FROM employees;

- GROUP BY: Groups rows that have the same values into summary rows.

     SELECT department, AVG(salary) FROM employees GROUP BY department;

7. Joins in SQL
Joins combine data from two or more tables:
- INNER JOIN: Retrieves records with matching values in both tables.

     SELECT employees.name, departments.department
FROM employees
INNER JOIN departments
ON employees.department_id = departments.id;

- LEFT JOIN: Retrieves all records from the left table and matched records from the right table.

     SELECT employees.name, departments.department
FROM employees
LEFT JOIN departments
ON employees.department_id = departments.id;

8. Inserting Data
To add new data to a table, you use the INSERT INTO statement:

   INSERT INTO employees (name, position, salary) VALUES ('John Doe', 'Analyst', 60000);

9. Updating Data
You can update existing data in a table using the UPDATE statement:

   UPDATE employees SET salary = 65000 WHERE name = 'John Doe';

10. Deleting Data
To remove data from a table, use the DELETE statement:

    DELETE FROM employees WHERE name = 'John Doe';


Here you can find essential SQL Interview Resources๐Ÿ‘‡
https://t.iss.one/DataSimplifier

Like this post if you need more ๐Ÿ‘โค๏ธ

Hope it helps :)
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SQL Checklist for Data Analysts ๐Ÿš€

๐ŸŒฑ Getting Started with SQL

๐Ÿ‘‰ Install SQL database software (MySQL, PostgreSQL, or SQL Server)
๐Ÿ‘‰ Set up your database environment and connect to your data

๐Ÿ” Load & Explore Data

๐Ÿ‘‰ Understand tables, rows, and columns
๐Ÿ‘‰ Use SELECT to retrieve data and LIMIT to get a sample view
๐Ÿ‘‰ Explore schema and table structure with DESCRIBE or SHOW COLUMNS

๐Ÿงน Data Filtering Essentials

๐Ÿ‘‰ Filter data using WHERE clauses
๐Ÿ‘‰ Use comparison operators (=, >, <) and logical operators (AND, OR)
๐Ÿ‘‰ Handle NULL values with IS NULL and IS NOT NULL

๐Ÿ”„ Transforming Data

๐Ÿ‘‰ Sort data with ORDER BY
๐Ÿ‘‰ Create calculated columns with AS and use arithmetic operators (+, -, *, /)
๐Ÿ‘‰ Use CASE WHEN for conditional expressions

๐Ÿ“Š Aggregation & Grouping

๐Ÿ‘‰ Summarize data with aggregation functions: SUM, COUNT, AVG, MIN, MAX
๐Ÿ‘‰ Group data with GROUP BY and filter groups with HAVING

๐Ÿ”— Mastering Joins

๐Ÿ‘‰ Combine tables with JOIN (INNER, LEFT, RIGHT, FULL OUTER)
๐Ÿ‘‰ Understand primary and foreign keys to create meaningful joins
๐Ÿ‘‰ Use SELF JOIN for analyzing data within the same table

๐Ÿ“… Date & Time Data

๐Ÿ‘‰ Convert dates and extract parts (year, month, day) with EXTRACT
๐Ÿ‘‰ Perform time-based analysis using DATEDIFF and date functions

๐Ÿ“ˆ Quick Exploratory Analysis

๐Ÿ‘‰ Calculate statistics to understand data distributions
๐Ÿ‘‰ Use GROUP BY with aggregation for category-based analysis

๐Ÿ“‰ Basic Data Visualizations (Optional)

๐Ÿ‘‰ Integrate SQL with visualization tools (Power BI, Tableau)
๐Ÿ‘‰ Create charts directly in SQL with certain extensions (like MySQL's built-in charts)

๐Ÿ’ช Advanced Query Handling

๐Ÿ‘‰ Master subqueries and nested queries
๐Ÿ‘‰ Use WITH (Common Table Expressions) for complex queries
๐Ÿ‘‰ Window functions for running totals, moving averages, and rankings (ROW_NUMBER, RANK, LAG, LEAD)

๐Ÿš€ Optimize for Performance

๐Ÿ‘‰ Index critical columns for faster querying
๐Ÿ‘‰ Analyze query plans and use optimizations
๐Ÿ‘‰ Limit result sets and avoid excessive joins for efficiency

๐Ÿ“‚ Practice Projects

๐Ÿ‘‰ Use real datasets to perform SQL analysis
๐Ÿ‘‰ Create a portfolio with case studies and projects

Here you can find SQL Interview Resources๐Ÿ‘‡
https://t.iss.one/DataSimplifier

Like this post if you need more ๐Ÿ‘โค๏ธ

Share with credits: https://t.iss.one/sqlspecialist

Hope it helps :)
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