constant.data.frame     Identify Constant Features of a Data Frame
dup.data.frame          Show records with duplicate or duplicated
                        values of grouping variables.
dupGroups.data.frame    Index records with with duplicate or duplicated
                        values of grouping variables.
enumerate               Count unique combinations of items in specified
                        columns.
ignore                  Drop columns in x that are present in y.
informative             Drop columns in x that are entirely NA.
informative.data.frame
                        Drop columns in x that are entirely NA.
itemize                 Show unique combinations of items in specified
                        columns
misplaced.data.frame    Index records whose relative positions would
                        change if sorted.
na.data.frame           Show records with NA values of grouping
                        variables.
naGroups.data.frame     Index records with NA values of grouping
                        variables.
safe_join.data.frame    Join Data Frames Safely
sort.grouped_df         Arrange by groups.
static                  Find unique records for subset of columns with
                        one unique value.
status.data.frame       Report status with respect to grouping
                        variables.
unsorted.data.frame     Extract records whose relative positions would
                        change if sorted.
weak.data.frame         Show records with NA, duplicate or duplicated
                        values of grouping variables.
