Group using .by

You can now also use the .by argument to group within a single operation, .by works with all verbs and has the advantage that you don’t need to use the .groups argument to suppress the grouping message or ungroup() when you’re done.

flights |> 
  summarize(
    delay = mean(dep_delay, na.rm = TRUE), 
    n = n(),
    .by = month
  )

## # A tibble: 12 × 3
##    month delay     n
##    <int> <dbl> <int>
##  1     1 10.0  27004
##  2    10  6.24 28889
##  3    11  5.44 27268
##  4    12 16.6  28135
##  5     2 10.8  24951
##  6     3 13.2  28834
##  7     4 13.9  28330
##  8     5 13.0  28796
##  9     6 20.8  28243
## 10     7 21.7  29425
## 11     8 12.6  29327
## 12     9  6.72 27574

Or if you want to group by multiple variables:

flights |> 
  summarize(
    delay = mean(dep_delay, na.rm = TRUE), 
    n = n(),
    .by = c(origin, dest)
  )

## # A tibble: 224 × 4
##    origin dest  delay     n
##    <chr>  <chr> <dbl> <int>
##  1 EWR    IAH   11.8   3973
##  2 LGA    IAH    9.06  2951
##  3 JFK    MIA    9.34  3314
##  4 JFK    BQN    6.67   599
##  5 LGA    ATL   11.4  10263
##  6 EWR    ORD   14.6   6100
##  7 EWR    FLL   13.5   3793
##  8 LGA    IAD   16.7   1803
##  9 JFK    MCO   10.6   5464
## 10 LGA    ORD   10.7   8857
## # ℹ 214 more rows