Lesson 65/100

Tutorials ML.NET Tutorial

NLP Text Classification — Complete Guide

NLP Text Classification — Complete Guide: free step-by-step lesson with examples, common mistakes, and interview tips — part of ML.NET Tutorial on Toolliyo Academy.

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ML.NET Tutorial · Lesson 65 of 100

NLP Text Classification

Foundations ✓Models ✓NLP & advancedMLOps

NLP & advanced · 3 — Recs, text, ONNX · ~10 min · Module 7: NLP with ML.NET

What is this?

Text classification assigns documents to categories — billing, fraud, shipping — from labeled examples.

Why should you care?

AIPredict routes support tickets automatically instead of manual queue sorting.

See it live — copy this example

Use a .NET console or Web API project with Microsoft.ML. Run dotnet run after pasting.

public class TicketRow { public string Subject; public string Body; public string Category; }
var pipe = ml.Transforms.Text.FeaturizeText("SubF", nameof(TicketRow.Subject))
    .Append(ml.Transforms.Text.FeaturizeText("BodyF", nameof(TicketRow.Body)))
    .Append(ml.Transforms.Concatenate("Features", "SubF", "BodyF"))
    .Append(ml.MulticlassClassification.Trainers.SdcaMaximumEntropy());
var model = pipe.Fit(tickets);

What happened?

  • Multi-class needs MapValueToKey on Label (trainer adds it).
  • Concatenate subject + body features for better accuracy.

Practice next

  1. Featurize subject and body.
  2. Concatenate Features.
  3. SdcaMaximumEntropy train.
  4. Add MapValueToKey on Category explicitly.
  5. Evaluate macro-F1.

Remember

Multi-class text. Concat fields. Sdca multi trainer.

AIPredict ticket router

New ticket auto-tagged Billing vs Fraud.

Outcome: Queue assignment without manual triage.

Interview prep for this lesson

Practice these questions aloud after reading—each links to a full structured answer.

Junior Detailed
Explain Concepts in the context of ML.NET.
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define Concepts…
Mid Detailed
What are common mistakes teams make with LLMs when using ML.NET?
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define LLMs in p…
Senior Detailed
How would you debug a production issue related to RAG in a ML.NET application?
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define RAG in pl…
Junior Detailed
Describe a real-world scenario where Production mattered in a ML.NET project.
Short answer: Interviewers want a crisp definition, a practical example from your projects, and awareness of trade-offs—not textbook dumps. Explain a bit more How to structure your answer (60–90 seconds) Define Productio…
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ML.NET Tutorial
Course syllabus
Module 1: ML.NET Foundations
Module 2: Machine Learning Basics
Module 3: ML.NET Pipelines
Module 4: Classification Models
Module 5: Regression Models
Module 6: Recommendation Systems
Module 7: NLP with ML.NET
Module 8: Advanced ML.NET
Module 9: ASP.NET Core AI Integration
Module 10: MLOps & Cloud AI
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