Merging & Joining Datasets

Summary

Combining multiple DataFrames via merges and joins (inner, outer, left, right) — how you'll build a single training table from scattered data sources.

• 1Practice all four join types on two related DataFrames and inspect the row counts.
• 2Learn to spot join issues: duplicate keys causing row explosion.
• 3Merge two real datasets on a shared key end-to-end.