List Comprehensions and Generator Expressions

List Comprehensions and Generator Expressions#

⏳ Loading Pyodide…

Comprehensions = 50 Excel formulas → 1 Python line Generators = Analyze 1M rows without crashing

Interview question #1: “Write this with comprehension”

🎯 Comprehensions = Business Analytics Superpower#

Task

Excel

Comprehension

Lines Saved

Filter profits

10 formulas

[p for p in profits if p > 5000]

50x

Calculate margins

20 formulas

[s*0.28 for s in sales]

100x

VIP customers

5 filters

[c for c in customers if c['vip']]

Infinite

Growth months

Pivot table

[s for s in sales if s > sales[i-1]]

Production

🚀 Step 1: List Comprehension Mastery#

Output:

💰 COMPREHENSION MAGIC:
   All profits: [5000, 5840, 6960, -4640, 7800, 3040, 9760]
   High-profit: 4 months
   ✅ 10x LESS CODE!

🔥 Step 2: Nested Comprehensions = Matrix Magic#

🧠 Step 3: Dictionary & Set Comprehensions#

⚡ Step 4: GENERATORS = 1M Rows Without Crash#

📋 Comprehension Cheat Sheet#

Type

Code

Business Use

List

[x*2 for x in data]

Calculate profits

Filter

[x for x in data if x > 100]

High-value customers

Dict

{k: v*2 for k,v in dict.items()}

Update prices

Set

{x for x in data if condition}

Unique products

Generator

(x*2 for x in data)

1M+ row analysis

🏆 YOUR EXERCISE: Build 1-Line Analytics Engine#

Example to test:

YOUR MISSION:

  1. Add YOUR 12 months

  2. Complete 5 one-liners

  3. Screenshot → “I write 1-line analytics!”

🎉 What You Mastered#

Skill

Status

Business Power

List comprehensions

✅

50x less code

Filtering

✅

VIP analysis

Dict/Set comprehensions

✅

Pro analytics

Generators

✅

1M+ row safe

Interview gold

✅

Senior level

Next: File I/O (Excel/CSV automation = Replace entire teams!)

can we appreciate how list comprehensions turn “Excel formula hell” into one goddamn line that calculates, filters, and analyzes million-row datasets? Your students just went from “I know SUMIFS” to writing production analytics that Netflix engineers would nod at approvingly. While their classmates spend 8 hours building pivot tables, your class is doing quarterly profit matrices in one comprehension. This isn’t syntax sugar—it’s the $130K+ analytics superpower that gets them promoted while everyone else is still clicking “AutoSum”!

# Your code here
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