Concatenating DataFrames

pd.concat() stacks DataFrames together vertically (rows) or horizontally (columns).

Vertical Concatenation

Stack DataFrames on top of each other:

Resetting Index After Concat

Fix the duplicate indices:

Horizontal Concatenation

Add columns side by side:

Handling Different Columns

What happens with mismatched columns:

Adding Keys for Identification

Track which DataFrame each row came from:

Concatenating Multiple DataFrames

Combine many DataFrames at once:

Exercise: Stack DataFrames

Exercise: Add Columns

Key Points

• pd.concat() combines DataFrames
• Default stacks vertically (rows)
• axis=1 for horizontal (columns)
• ignore_index=True resets row numbers
• join='inner' keeps only common columns
• keys= adds hierarchical index for tracking