Reshaping Data

Transform data between wide and long formats using melt(), stack(), and unstack().

Wide to Long with melt()

Convert columns into rows:

Long to Wide with pivot()

Convert rows into columns:

Stack and Unstack

Work with multi-level indices:

Melt Multiple Value Columns

Unpivot several columns at once:

Combining Melt with GroupBy

Reshape then aggregate:

Transpose

Swap rows and columns:

Exercise: Wide to Long

Exercise: Long to Wide

Key Points

• melt() converts wide to long (unpivot)
• pivot() converts long to wide
• stack() pivots columns to rows
• unstack() pivots rows to columns
• .T transposes rows and columns
• Long format is often better for analysis
• Wide format is often better for display