Consider options for editing a pivot table after it has been calculated

[cbailiss]

For background, see:
https://stackoverflow.com/questions/62452034/can-we-replace-a-column-from-a-pivot-table-created-using-pivottabler-package

Example that doesn't work:

removeAllColumnGroups <- function(pt)
{
  while(pt$columnGroup$childGroupCount > 0) {
    pt$columnGroup$removeChildGroup(index=pt$columnGroup$childGroupCount)
  }
}

pt <- PivotTable$new()
pt$addData(bhmtrains)
pt$addColumnDataGroups("TrainCategory")
pt$addRowDataGroups("TOC")
pt$defineCalculation(calculationName="TotalTrains", summariseExpression="n()")
pt$renderPivot()

removeAllColumnGroups(pt)
pt$renderPivot()

# need to reapply the calculations as those cells have been lost
pt$addColumnDataGroups("TrainCategory")
pt$defineCalculation(calculationName="TotalTrains", summariseExpression="n()")
pt$renderPivot()

Is there an easy way to clear the cells from the pivot table (to allow the rows and columns to be amended) then reapply the calculations (on the same axis as they were originally applied, in the same order?)

Or is all this just too complicated and not worth doing?

Consider adding pt$clearColumnGroups(), pt$clearRowGroups().