Add log about ungroup()

[damianooldoni]

While doing this:

df %>% 
  group_by() %>% 
  summarize() %>% 
  ungroup()

I get this as last message: summarize: now xx rows and yy columns, zz group variables remaining, where xx, yy and zz are numbers.
It would be nice, I think, to have a message for ungroup() as well.
Something like: ungroup: no grouping variables left or just ungrouped.
What do you think? Thanks.

[elbersb]

Yes, this is probably a good idea. In the beginning I was reluctant to add logs for these trivial commands, but it makes the package more consistent. Not sure when I get around to this. As always, open to PRs as well.

[damianooldoni]

I will give a try.

[elbersb]

closed in #33