Configuration
| Option | Description | Default |
|---|---|---|
| Axis | Rows (vertical stack) — adds rows. Columns (horizontal stack) — adds columns side by side. | Rows |
| Ignore Index | Reset the row index in the result | Yes |
| Join | outer keeps all columns (fills NaN for missing). inner keeps only shared columns. | outer |
Input / Output
| Type | |
|---|---|
| Input | First DataFrame + Second DataFrame |
| Output | DataFrame |
When to use
- Vertical (rows): Combine two CSV files that have the same columns (e.g. January data + February data).
- Horizontal (columns): Attach a new set of columns to an existing DataFrame when rows are already aligned.