prAddEmptyVals: Convert the by-list into a matrix compatible format
Description
Helper for [getDescriptionStatsBy] that fixes empty values in matrix
so that they are compatible with the matrix
Usage
prAddEmptyVals(t, missing_value)
Arguments
- t
Output from [prNumericDescs], [prPropDescs], or [prFactorDescs].
- missing_value
Value that is substituted for empty cells. Defaults to "-"