addVolumesToHierarchy is too specific

[bcdarwin]

It can only accumulate by sum rather than mean, volume-weighted mean, etc. (in which case it's ambiguous whether it should be renamed...).

[bcdarwin]

From the documentation:

Currently propagates volumes up the tree by summing. Future versions will add propagating through weighted means or other functions

[bcdarwin]

Maybe something like addObservationsToLeaves <- function (hdefs, obs_matrix, colname) { ...error checking and assigning observations into leaves as in addHierarchyToVolumes...} is sufficient, or addObservationsToHierarchy also accepting combining functions. We would then generalize hanatLm via optional colname = "volumes" argument.