use-group-by-n.md

library(tidyverse)
df <- tibble(x = c(1,1,2,2))

df |> 
  group_by(x) |> 
  mutate(
    n = n(),
    rown = row_number(),
    max_row_n = max(row_number())
  ) |> 
    add_count(x)
#> Storing counts in `nn`, as `n` already present in input
#> ℹ Use `name = "new_name"` to pick a new name.
#> # A tibble: 4 × 5
#> # Groups:   x [2]
#>       x     n  rown max_row_n    nn
#>   <dbl> <int> <int>     <int> <int>
#> 1     1     2     1         2     2
#> 2     1     2     2         2     2
#> 3     2     2     1         2     2
#> 4     2     2     2         2     2

^{Created on 2025-07-08 with reprex v2.1.1}

Session info

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
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#>  language (EN)
#>  collate  en_AU.UTF-8
#>  ctype    en_AU.UTF-8
#>  tz       Australia/Hobart
#>  date     2025-07-08
#>  pandoc   3.6.3 @ /Applications/Positron.app/Contents/Resources/app/quarto/bin/tools/aarch64/ (via rmarkdown)
#>  quarto   1.7.31 @ /usr/local/bin/quarto
#> 
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#> ──────────────────────────────────────────────────────────────────────────────

njtierney/use-group-by-n.md