Merging DataFrames

pd.merge() combines DataFrames by matching values in columns, similar to SQL JOINs.

Basic Merge

Join on a common column:

Different Column Names

Merge when key columns have different names:

Merge on Multiple Columns

Match on more than one column:

Handling Duplicate Column Names

When both DataFrames have columns with the same name:

Merge with Index

Use index as join key:

Validate Merge

Check merge relationship:

Exercise: Basic Merge

Exercise: Different Column Names

Key Points

• pd.merge() joins on matching column values
• on= when column names are the same
• left_on= / right_on= for different names
• Default is inner join (only matching rows)
• suffixes= handles duplicate column names
• left_index=True / right_index=True for index joins