Phase 3: Data Visualization · ~25 minutes · Python · matplotlib

Figures and Axes, the Object-Oriented Way

plt.plot() doesn't ask which figure you meant. It draws on whichever one happens to be 'current' — and forgetting that is the single most common way a second plot silently ruins the first.

Hiring signal: Reaches for fig, ax = plt.subplots() by default, specifically because it names which axes every draw call targets instead of relying on implicit global state

What you will learn

Build a plot using the object-oriented fig, ax = plt.subplots() pattern
Explain what pyplot's global 'current figure' state actually is
Diagnose why a second plt.plot() call silently drew onto the first figure instead of a new one
Extend a single plot into multiple side-by-side subplots using the OO pattern

Introduction

Type: Learn Languages: Python, matplotlib Prerequisites: Phase 02 (NumPy for Data) Time: ~25 minutes

Objective

Learning objectives

Build a plot using the object-oriented fig, ax = plt.subplots() pattern
Explain what pyplot's global "current figure" state actually is
Diagnose why a second plt.plot() call silently drew onto the first figure instead of a new one
Extend a single plot into multiple side-by-side subplots using the OO pattern

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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