7.4 group functions

7.4.1 group_map、group_modify

group_map(), group_modify() and group_walk() are purrr-style functions that can be used to iterate on grouped tibbles.

This is similar to split() and then map():

7.4.2 group_nest、group_split、group_keys、group_data

group_nest() is similar to group_by() + tidyr::nest():

group_split() is a tidy version of base::split(). In particular, it respects a group_by()-like grouping specification, and refuses to name its result.

only grouping variables:

only rows: