Can I modify an entire column from a dataset with system.dataset.setValue()?

Ignition
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3 
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:

# usage:
def updateColumn(value):
	return value * 2

updatedDs = mapColumn(updateColumn, ds, "b")

On my test dataset, this does what you'd expect:

a | b | c
1 | 2 | 3
4 | 5 | 6

a | b | c
1 | 4 | 3
4 | 10 | 6
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