Perform an operation with temporary groups

This is an experimental new function that allows you to modify the grouping variables for a single operation.

with_groups(.data, .groups, .f, ...)

Arguments

.data

A data frame

.groups

<tidy-select> One or more variables to group by. Unlike group_by(), you can only group by existing variables, and you can use tidy-select syntax like c(x, y, z) to select multiple variables.

Use NULL to temporarily ungroup.

.f

Function to apply to regrouped data. Supports purrr-style ~ syntax

...

Additional arguments passed on to ....

Examples

df <- tibble(g = c(1, 1, 2, 2, 3), x = runif(5))
df %>%
  with_groups(g, mutate, x_mean = mean(x))
#> # A tibble: 5 × 3
#>       g      x x_mean
#>   <dbl>  <dbl>  <dbl>
#> 1     1 0.710   0.528
#> 2     1 0.346   0.528
#> 3     2 0.0221  0.329
#> 4     2 0.636   0.329
#> 5     3 0.112   0.112
df %>%
  with_groups(g, ~ mutate(.x, x1 = first(x)))
#> # A tibble: 5 × 3
#>       g      x     x1
#>   <dbl>  <dbl>  <dbl>
#> 1     1 0.710  0.710 
#> 2     1 0.346  0.710 
#> 3     2 0.0221 0.0221
#> 4     2 0.636  0.0221
#> 5     3 0.112  0.112 

df %>%
  group_by(g) %>%
  with_groups(NULL, mutate, x_mean = mean(x))
#> # A tibble: 5 × 3
#> # Groups:   g [3]
#>       g      x x_mean
#>   <dbl>  <dbl>  <dbl>
#> 1     1 0.710   0.365
#> 2     1 0.346   0.365
#> 3     2 0.0221  0.365
#> 4     2 0.636   0.365
#> 5     3 0.112   0.365

# NB: grouping can't be restored if you remove the grouping variables
df %>%
  group_by(g) %>%
  with_groups(NULL, mutate, g = NULL)
#> # A tibble: 5 × 1
#>        x
#>    <dbl>
#> 1 0.710 
#> 2 0.346 
#> 3 0.0221
#> 4 0.636 
#> 5 0.112