Number of observations in each group

Helper function that can be used to find counts by group.

Can be used inside summarize(), mutate(), & filter()

n.()

Examples

df <- data.table(
  x = 1:3,
  y = 4:6,
  z = c("a","a","b")
 )

df %>%
  summarize(count = n(), .by = z)
#> # A tidytable: 2 × 2
#>   z     count
#>   <chr> <int>
#> 1 a         2
#> 2 b         1