Feature Engineering

What is Feature Engineering?

Feature Engineering means feature engineering creates useful input columns from raw data to improve model performance.

In real programs, this topic helps in creating better input columns. Learn the idea first, then type the program yourself and compare the output.

Why should you learn this?

• It is useful for creating better input columns.
• It connects with encoding categories.
• It improves your ability to read, write and debug Python programs.

Important Terms

These terms are used directly in this lesson. Understand them before memorising the code.

Syntax / Basic Pattern

The simple pattern is: prepare data, apply the concept, then show the result.

import pandas as pd
df = pd.DataFrame({"StudyHours": [2, 4, 6], "Attendance": [70, 85, 95]})
df["Study_Attendance_Score"] = df["StudyHours"] * df["Attendance"]
print(df)

Complete Example Program

import pandas as pd

df = pd.DataFrame({"StudyHours": [2, 4, 6], "Attendance": [70, 85, 95]})

df["Study_Attendance_Score"] = df["StudyHours"] * df["Attendance"]
print(df)

Expected Output

Program Explanation

• import pandas as pd imports ready-made features from a module/library.
• df = pd.DataFrame({"StudyHours": [2, 4, 6], "Attendance": [70, 85, 95]}) stores a value in df.
• df["Study_Attendance_Score"] = df["StudyHours"] * df["Attendance"] stores a value in df["Study_Attendance_Score"].
• print(df) displays information or calculated result on the screen.

Where will you use it?

• Creating better input columns.
• Encoding categories.
• Improving model performance.

Common Mistakes

• Analysing data before checking missing values, duplicates and data types.
• Changing original data without keeping a clean copy.
• Creating charts without title, labels or explanation.

Practice Tasks

1. Type the program in feature-engineering.py and run it.
2. Change input values or sample data and observe the new output.
3. Create one example related to creating better input columns.
4. Write 5 lines explaining the logic in your own words.

Summary

Feature Engineering is not a theory-only topic. You should be able to explain the meaning, write the example, run it successfully, and use it in a small practical program.