# Can I modify an entire column from a dataset with system.dataset.setValue()? **URL:** \ **Category:** Ignition\ **Tags:** python, vision, scripting\ **Created:** [March 8, 2024, 3:39pm UTC](https://forum.inductiveautomation.com/t/can-i-modify-an-entire-column-from-a-dataset-with-system-dataset-setvalue/87043 "2024-03-08T15:39:29Z")\ **Posts on this page:** 1\ **Showing post:** 3
**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\ **Post date:** [March 8, 2024, 4:23pm UTC](https://forum.inductiveautomation.com/t/can-i-modify-an-entire-column-from-a-dataset-with-system-dataset-setvalue/87043/3 "2024-03-08T16:23:52Z")
```python def mapColumn(function, dataset, column): if isinstance(column, basestring): column = dataset.getColumnIndex(column) columnData = map(function, dataset.getColumnAsList(column)) columnsToKeep = range(dataset.columnCount) columnsToKeep.pop(column) dsWithoutColumn = system.dataset.filterColumns(dataset, columnsToKeep) return system.dataset.addColumn( dsWithoutColumn, column, columnData, dataset.getColumnName(column), dataset.getColumnType(column) ) ``` It's relatively easy to create a 'mapColumn' function composed of our base primitives. This will be pretty efficient. Usage is pretty simple - just declare a function that performs the calculation you want, for each value in the column, then supply it (no parenthesis!) to the mapColumn function: ```python # usage: def updateColumn(value): return value * 2 updatedDs = mapColumn(updateColumn, ds, "b") ``` On my test dataset, this does what you'd expect: ```auto a | b | c 1 | 2 | 3 4 | 5 | 6 a | b | c 1 | 4 | 3 4 | 10 | 6 ``` --- _[View the full topic](https://forum.inductiveautomation.com/t/can-i-modify-an-entire-column-from-a-dataset-with-system-dataset-setvalue/87043)._