Categorical Arrays in MATLAB

🏷️ Categorical Arrays in MATLAB

They are memory-efficient and enable group-wise analysis and plotting.
MATLAB is developed by MathWorks.

🔹 What Is a Categorical Array?

A categorical array:

• Stores data as labels (categories) instead of raw text

• Supports ordered/unordered categories

• Is ideal for grouping, statistics, and plots

📌 Example categories: "Male" / "Female", "Pass" / "Fail", "A / B / C"

1️⃣ Create a Categorical Array

🔸 From Strings

Output

🔸 From Cell Array of Char

🔸 Specify Categories Explicitly

2️⃣ View Categories

3️⃣ Count Each Category

4️⃣ Rename Categories

5️⃣ Reorder Categories

Useful for ordered data.

6️⃣ Ordinal (Ordered) Categorical

📌 Enables logical comparisons:

7️⃣ Convert Between Types

🔸 String → Categorical

8️⃣ Categorical with Tables

Very common in real datasets.

9️⃣ Plotting with Categorical Data

📌 MATLAB automatically groups by category.

⚠️ Important Notes

• Faster & safer than raw strings for grouping

• Ideal for tables, statistics, plots

• Supports missing values: <undefined>

• Use ordinal only when order matters

🎯 Interview Questions: Categorical Arrays

🔹 Q1. What is a categorical array?

Answer:
A data type for storing discrete labeled categories.

🔹 Q2. Difference between string and categorical?

Answer:
Strings store text; categoricals store labels with grouping logic.

🔹 Q3. How do you count categories?

Answer:
Using countcats().

🔹 Q4. What is an ordinal categorical?

Answer:
A categorical array with a defined order.

🔹 Q5. How do you rename categories?

Answer:
Using renamecats().

🔹 Q6. Where are categorical arrays commonly used?

Answer:
Tables, plots, statistical grouping, real-world datasets.

✅ Summary

• Categorical arrays handle discrete labels

• Memory-efficient and analysis-friendly

• Support ordering, counting, renaming

• Essential for data science & statistics in MATLAB