Phase 1: pandas Mastery · ~30 minutes · Python · pandas

Selecting and Filtering

Under pandas 3.0, chained assignment doesn't crash — it warns, silently doesn't touch your data, and lets your script keep running as if it worked.

Hiring signal: Writes .loc assignment as the default pattern from the start, and knows that a pandas warning during assignment means 'verify the change actually happened,' not just 'read the warning text'

What you will learn

Filter a DataFrame using boolean indexing
Select and modify data correctly using .loc
Explain what pandas 3.0's Copy-on-Write actually does to chained assignment
Diagnose whether a given assignment pattern will warn-and-silently-fail, or genuinely work

Introduction

Type: Learn Languages: Python, pandas Prerequisites: Phase 00 (Working with Data in Python) Time: ~30 minutes

Objective

Learning objectives

Filter a DataFrame using boolean indexing
Select and modify data correctly using .loc
Explain what pandas 3.0's Copy-on-Write actually does to chained assignment
Diagnose whether a given assignment pattern will warn-and-silently-fail, or genuinely work

Unlock the full lesson

You've read the first 2 sections. The rest of this lesson covers The Problem, The Concept, Build, Key Terms & Next — plus a hands-on lab, quiz, and project artifact.

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