This is an accessor and replacement method for the aqp_df_class
entry in the metadata slot. This entry is used internally by methods that interact with data.frame
objects and slots to ensure that the same class used to promote to the SoilProfileCollection initially is used throughout the process.
# S4 method for SoilProfileCollection
aqp_df_class(object)# S4 method for SoilProfileCollection
aqp_df_class(object) <- value
a SoilProfileCollection
"data.frame", "data.table" or "tbl_df"