arrange not reporting syntax errors on .by_group

[py9mrg]

Hello,

When using arrange on grouped data (and wanting to respect the grouping), we need to use the .by_group argument. However, if you make a syntax error - e.g. by_group or .by_groups - then the arranging fails to respect the groups silently. This has the potential to lead to serious errors in analysis.

library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

# correct behaviour
mtcars |>
  group_by(cyl) |>
  arrange(mpg, .by_group = TRUE)
#> # A tibble: 32 × 11
#> # Groups:   cyl [3]
#>      mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  21.4     4 121     109  4.11  2.78  18.6     1     1     4     2
#>  2  21.5     4 120.     97  3.7   2.46  20.0     1     0     3     1
#>  3  22.8     4 108      93  3.85  2.32  18.6     1     1     4     1
#>  4  22.8     4 141.     95  3.92  3.15  22.9     1     0     4     2
#>  5  24.4     4 147.     62  3.69  3.19  20       1     0     4     2
#>  6  26       4 120.     91  4.43  2.14  16.7     0     1     5     2
#>  7  27.3     4  79      66  4.08  1.94  18.9     1     1     4     1
#>  8  30.4     4  75.7    52  4.93  1.62  18.5     1     1     4     2
#>  9  30.4     4  95.1   113  3.77  1.51  16.9     1     1     5     2
#> 10  32.4     4  78.7    66  4.08  2.2   19.5     1     1     4     1
#> # ℹ 22 more rows

# syntax error leads to no grouping, but happens silently
mtcars |>
  group_by(cyl) |>
  arrange(mpg, .by_groups = TRUE)
#> # A tibble: 32 × 11
#> # Groups:   cyl [3]
#>      mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#>  1  10.4     8  472    205  2.93  5.25  18.0     0     0     3     4
#>  2  10.4     8  460    215  3     5.42  17.8     0     0     3     4
#>  3  13.3     8  350    245  3.73  3.84  15.4     0     0     3     4
#>  4  14.3     8  360    245  3.21  3.57  15.8     0     0     3     4
#>  5  14.7     8  440    230  3.23  5.34  17.4     0     0     3     4
#>  6  15       8  301    335  3.54  3.57  14.6     0     1     5     8
#>  7  15.2     8  276.   180  3.07  3.78  18       0     0     3     3
#>  8  15.2     8  304    150  3.15  3.44  17.3     0     0     3     2
#>  9  15.5     8  318    150  2.76  3.52  16.9     0     0     3     2
#> 10  15.8     8  351    264  4.22  3.17  14.5     0     1     5     4
#> # ℹ 22 more rows

^{Created on 2024-01-08 with reprex v2.0.2}

I assume this is happening because of the ... argument combined with passing an object set to TRUE. I think there needs to be something here that either checks for arguments similar to .by_group but miss-spelt, or some other method to warn / throw an error in such circumstances. Failing to group silently seems a bit dangerous.

[philibe]

For me your .by_groups is understood as unknown parameter, and maybe as column, and skipped in the condition below.

dplyr/R/arrange.R

Line 88 in b359331

arrange.data.frame <- function(.data,

arrange.data.frame <- function(.data,
                               ...,
                               .by_group = FALSE,
                               .locale = NULL) {
  dots <- enquos(...)

  if (.by_group) {  ## my remark : skipped if .by_groups
    dots <- c(quos(!!!groups(.data)), dots)
  }

  loc <- arrange_rows(.data, dots = dots, locale = .locale)
  dplyr_row_slice(.data, loc)
}

Why to have a warning for everything ? To type .by_groups is a typo. End of the story.