| by_row | Apply a function to each row of a data frame | 
| by_slice | Apply a function to slices of a data frame | 
| dmap | Map over the columns of a data frame | 
| dmap_at | Map over the columns of a data frame | 
| dmap_if | Map over the columns of a data frame | 
| invoke_rows | Apply a function to each row of a data frame | 
| map_rows | Apply a function to each row of a data frame | 
| slice_rows | Slice a data frame into groups of rows | 
| unslice | Slice a data frame into groups of rows |