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Data Science & Machine Learning
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🔥 OpenCV – Computer Vision Library 👁️‍🗨️

OpenCV (Open Source Computer Vision Library) is an open-source library used for real-time image processing and computer vision applications.

🔹 Why Use OpenCV?
✔️ Fast image/video processing
✔️ Large collection of functions (face detection, object tracking, etc.)
✔️ Works with NumPy arrays
✔️ Cross-platform support
✔️ Integrates with deep learning models (e.g. with TensorFlow, PyTorch)

🔸 Installation
pip install opencv-python

🔸 Basic Example: Load & Display Image
import cv2

img = cv2.imread('image.jpg') # Load image
cv2.imshow('Image', img) # Display
cv2.waitKey(0) # Wait for key press
cv2.destroyAllWindows() # Close window


🔸 Read from Webcam & Convert to Grayscale
cap = cv2.VideoCapture(0)

while True:
    ret, frame = cap.read()
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
    cv2.imshow('Grayscale Video', gray)

    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()


🔹 Popular Features
✔️ Face Detection (Haar Cascades)
✔️ Edge Detection (Canny)
✔️ Object Tracking
✔️ Image Filtering (Blur, Sharpen)
✔️ Drawing shapes & text on images

🔹 Real-World Use Cases
✔️ Facial recognition systems
✔️ Surveillance cameras
✔️ Self-driving cars
✔️ Augmented reality

🔹 Summary

Ideal For: Developers working with images/videos or real-time vision apps
Strength: Fast processing, huge toolkit, active community

Python Resources: https://whatsapp.com/channel/0029VaiM08SDuMRaGKd9Wv0L

💬 Tap ❤️ for more!
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📈 Predictive Modeling for Future Stock Prices in Python: A Step-by-Step Guide

The process of building a stock price prediction model using Python.

1. Import required modules

2. Obtaining historical data on stock prices

3. Selection of features.

4. Definition of features and target variable

5. Preparing data for training

6. Separation of data into training and test sets

7. Building and training the model

8. Making forecasts

9. Trading Strategy Testing
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Data Analyst Roadmap

Like if it helps ❤️
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Here are some tricky🧩 SQL interview questions!

1. Find the second-highest salary in a table without using LIMIT or TOP.

2. Write a SQL query to find all employees who earn more than their managers.

3. Find the duplicate rows in a table without using GROUP BY.

4. Write a SQL query to find the top 10% of earners in a table.

5. Find the cumulative sum of a column in a table.

6. Write a SQL query to find all employees who have never taken a leave.

7. Find the difference between the current row and the next row in a table.

8. Write a SQL query to find all departments with more than one employee.

9. Find the maximum value of a column for each group without using GROUP BY.

10. Write a SQL query to find all employees who have taken more than 3 leaves in a month.

These questions are designed to test your SQL skills, including your ability to write efficient queries, think creatively, and solve complex problems.

Here are the answers to these questions:

1. SELECT MAX(salary) FROM table WHERE salary NOT IN (SELECT MAX(salary) FROM table)

2. SELECT e1.* FROM employees e1 JOIN employees e2 ON e1.manager_id = (link unavailable) WHERE e1.salary > e2.salary

3. SELECT * FROM table WHERE rowid IN (SELECT rowid FROM table GROUP BY column HAVING COUNT(*) > 1)

4. SELECT * FROM table WHERE salary > (SELECT PERCENTILE_CONT(0.9) WITHIN GROUP (ORDER BY salary) FROM table)

5. SELECT column, SUM(column) OVER (ORDER BY rowid) FROM table

6. SELECT * FROM employees WHERE id NOT IN (SELECT employee_id FROM leaves)

7. SELECT *, column - LEAD(column) OVER (ORDER BY rowid) FROM table

8. SELECT department FROM employees GROUP BY department HAVING COUNT(*) > 1

9. SELECT MAX(column) FROM table WHERE column NOT IN (SELECT MAX(column) FROM table GROUP BY group_column)
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🚨Here is a comprehensive list of #interview questions that are commonly asked in job interviews for Data Scientist, Data Analyst, and Data Engineer positions:


➡️ Data Scientist Interview Questions



Technical Questions

1) What are your preferred programming languages for data science, and why?

2) Can you write a Python noscript to perform data cleaning on a given dataset?

3) Explain the Central Limit Theorem.

4) How do you handle missing data in a dataset?

5) Describe the difference between supervised and unsupervised learning.

6) How do you select the right algorithm for your model?


Questions Related To Problem-Solving and Projects

7) Walk me through a data science project you have worked on.

8) How did you handle data preprocessing in your project?

9) How do you evaluate the performance of a machine learning model?

10) What techniques do you use to prevent overfitting?


➡️Data Analyst Interview Questions


Technical Questions


1) Write a SQL query to find the second highest salary from the employee table.

2) How would you optimize a slow-running query?

3) How do you use pivot tables in Excel?

4) Explain the VLOOKUP function.

5) How do you handle outliers in your data?

6) Describe the steps you take to clean a dataset.


Analytical Questions

7) How do you interpret data to make business decisions?

8) Give an example of a time when your analysis directly influenced a business decision.

9) What are your preferred tools for data analysis and why?

10) How do you ensure the accuracy of your analysis?


➡️Data Engineer Interview Questions


Technical Questions


1) What is your experience with SQL and NoSQL databases?

2) How do you design a scalable database architecture?

3) Explain the ETL process you follow in your projects.

4) How do you handle data transformation and loading efficiently?

5) What is your experience with Hadoop/Spark?

6) How do you manage and process large datasets?


Questions Related To Problem-Solving and Optimization

7) Describe a data pipeline you have built.

8) What challenges did you face, and how did you overcome them?

9) How do you ensure your data processes run efficiently?

10) Describe a time when you had to optimize a slow data pipeline.

I have curated top-notch Data Analytics Resources 👇👇
https://whatsapp.com/channel/0029VaGgzAk72WTmQFERKh02

Hope this helps you 😊
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Here is a list of 100 data science interview questions that can help you prepare for a data science job interview. These questions cover a wide range of topics and levels of difficulty, so be sure to review them thoroughly and practice your answers. 📱

Mathematics and Statistics:

1. What is the Central Limit Theorem, and why is it important in statistics?
2. Explain the difference between population and sample.
3. What is probability and how is it calculated?
4. What are the measures of central tendency, and when would you use each one?
5. Define variance and standard deviation.
6. What is the significance of hypothesis testing in data science?
7. Explain the p-value and its significance in hypothesis testing.
8. What is a normal distribution, and why is it important in statistics?
9. Describe the differences between a Z-score and a T-score.
10. What is correlation, and how is it measured?
11. What is the difference between covariance and correlation?
12. What is the law of large numbers?

Machine Learning:

13. What is machine learning, and how is it different from traditional programming?
14. Explain the bias-variance trade-off.
15. What are the different types of machine learning algorithms?
16. What is overfitting, and how can you prevent it?
17. Describe the k-fold cross-validation technique.
18. What is regularization, and why is it important in machine learning?
19. Explain the concept of feature engineering.
20. What is gradient descent, and how does it work in machine learning?
21. What is a decision tree, and how does it work?
22. What are ensemble methods in machine learning, and provide examples.
23. Explain the difference between supervised and unsupervised learning.
24. What is deep learning, and how does it differ from traditional neural networks?
25. What is a convolutional neural network (CNN), and where is it commonly used?
26. What is a recurrent neural network (RNN), and where is it commonly used?
27. What is the vanishing gradient problem in deep learning?
28. Describe the concept of transfer learning in deep learning.

Data Preprocessing:

29. What is data preprocessing, and why is it important in data science?
30. Explain missing data imputation techniques.
31. What is one-hot encoding, and when is it used?
32. How do you handle categorical data in machine learning?
33. Describe the process of data normalization and standardization.
34. What is feature scaling, and why is it necessary?
35. What is outlier detection, and how can you identify outliers in a dataset?

Data Exploration:

36. What is exploratory data analysis (EDA), and why is it important?
37. Explain the concept of data distribution.
38. What are box plots, and how are they used in EDA?
39. What is a histogram, and what insights can you gain from it?
40. Describe the concept of data skewness.
41. What are scatter plots, and how are they useful in data analysis?
42. What is a correlation matrix, and how is it used in EDA?
43. How do you handle imbalanced datasets in machine learning?

Model Evaluation:

44. What are the common metrics used for evaluating classification models?
45. Explain precision, recall, and F1-score.
46. What is ROC curve analysis, and what does it measure?
47. How do you choose the appropriate evaluation metric for a regression problem?
48. Describe the concept of confusion matrix.
49. What is cross-entropy loss, and how is it used in classification problems?
50. Explain the concept of AUC-ROC.

Python and Programming:
51. Describe the differences between Python 2 and Python 3.
52. What is the Global Interpreter Lock (GIL) in Python, and how does it affect multi-threading?
53. Explain the use of decorators in Python.
54. What are list comprehensions, and how do they work?
55. Describe the purpose of virtual environments in Python.
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