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Why These 25?

Hand-curated for maximum interview ROI.

Multi-FK Industry Schemas

Every problem composes 2–4 merges across the same kind of 8–15 table relational structures you’d see at a Stripe, Airbnb, or Uber. Not toy 2-DataFrame examples — actual multi-table joins.

The Real Merge Failure Modes

Row explosion from many-to-many joins. Silent column overrides. Indexes-don’t-match. The traps that crash production pipelines but get ignored in tutorials — you see them, feel them, and learn to spot them in your own code.

Anti-Merge → Feature-Matrix Capstones

Stage 4 drills the canonical anti-merge (indicator=True + filter _merge=='left_only') — the pandas equivalent of LEFT JOIN + IS NULL. Stage 5 then chains 4–5 merges with classification and feature engineering into production-grade feature matrices.

Skill Coverage

How the 25 problems distribute across pandas topics.

Basic Inner Merge
5
Two-Merge Pipelines
5
Multi-Table 3+ Merges
5
Anti-Merge (indicator=True + left_only)
5
Complex Pipelines with Classification
3
Complex Pipelines with Feature Engineering
2

FAQ

Helpful but not required.

If you can write basic boolean filtering (df[df[col]==X]), start here.

Stage 1 begins with the simplest 2-table inner merge.

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LDS Pandas Merge 25 — 25 Curated Python Problems

A 5-stage progression on pandas merge: 2-table inner merges, chained 2-3-4 table pipelines, anti-merges with `indicator=True`, and the 4-5 merge feature-matrix pipelines that stitch a production DataFrame together. Twenty-five problems on 15 industry-grade schemas — the pandas equivalent of getting SQL joins right.

Problems included in LDS Pandas Merge 25

  1. Accounts With Customer Names
  2. Charges With Merchant Names
  3. Listings With Property Details
  4. Posts With Author Names
  5. Subscriptions with Plan Names
  6. Click Path with Advertiser
  7. Claim Details With Provider and Plan
  8. Order Details With Restaurant and Customer
  9. Inquiry-to-Tour Pipeline
  10. Usage with Plan Info
  11. Position Details With Full Hierarchy
  12. Full Reservation Hierarchy
  13. Full Order Line Detail
  14. Subscription Full Hierarchy
  15. Session Full Hierarchy
  16. Creative Assets Not Used in Ads
  17. Procedures Without Any Claims
  18. Menu Items Without Orders
  19. Drivers Without Trips
  20. Products Without Orders
  21. Campaign Health Classification System
  22. Cross-Provider Claims Analysis
  23. Buyer Journey Analysis
  24. Revenue Pipeline Analysis
  25. User Feature Matrix