Can derived calculations refer to each other?

[cbailiss]

Is it possible to separate the Percent calculation below into two separate derived calculations?

library(pivottabler)

pt <- PivotTable$new()
pt$addData(mtcars)
pt$addColumnDataGroups("am")
pt$addRowDataGroups("vs")
pt$addRowDataGroups("mpg", totalCaption= "Subtotal") 
pt$addRowDataGroups("disp", addTotal=FALSE)

# basic calculation
pt$defineCalculation(calculationName="CountVal", summariseExpression="n()", visible=FALSE)

# get column totals
filterOverrides <- PivotFilterOverrides$new(pt, keepOnlyFiltersFor="am")
pt$defineCalculation(calculationName="CountAll", summariseExpression="n()", filters=filterOverrides, visible=FALSE)

# percentage of column calculation total
pt$defineCalculation(calculationName="Percent", caption="Percent",
                     type="calculation", basedOn=c("CountVal", "CountAll"),
                     calculationExpression="paste0(values$CountVal, ' (', sprintf('%.1f %%', values$CountVal/values$CountAll*100), ')')")

pt$renderPivot()