# Column.is_null
URL: https://lsd.tools/docs/api-column-is-null
Updated: 2026-07-17

## Example

```python
t.filter(t["score"].is_null())      # keep only the rows missing a score
```

## Notes

Produces a boolean `Column` (a mask) you pass to [`filter`](/docs/api-table-filter). It is the
exact complement of [`is_valid`](/docs/api-column-is-valid). For a per-column count of nulls
across the whole table, use [`Table.null_report`](/docs/api-table-null-report).

## See also

**API:** [is_valid](/docs/api-column-is-valid) · [Table.filter](/docs/api-table-filter) · [Table.null_report](/docs/api-table-null-report)

**Guides:** [Tables & data flow](/docs/tools-tables) · [Clean a CSV](/docs/ex-clean-csv)