[Superseded]

do() is superseded as of dplyr 1.0.0, because its syntax never really felt like it belong with the rest of dplyr. It's replaced by a combination of summarise() (which can now produce multiple rows and multiple columns), nest_by() (which creates a rowwise tibble of nested data), and across() (which allows you to access the data for the "current" group).

do(.data, ...)

Arguments

.data

a tbl

...

Expressions to apply to each group. If named, results will be stored in a new column. If unnamed, should return a data frame. You can use . to refer to the current group. You can not mix named and unnamed arguments.

Examples

# do() with unnamed arguments becomes summarise()
# . becomes across()
by_cyl <- mtcars %>% group_by(cyl)
by_cyl %>% do(head(., 2))
#> # A tibble: 6 x 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  22.8     4  108     93  3.85  2.32  18.6     1     1     4     1
#> 2  24.4     4  147.    62  3.69  3.19  20       1     0     4     2
#> 3  21       6  160    110  3.9   2.62  16.5     0     1     4     4
#> 4  21       6  160    110  3.9   2.88  17.0     0     1     4     4
#> 5  18.7     8  360    175  3.15  3.44  17.0     0     0     3     2
#> 6  14.3     8  360    245  3.21  3.57  15.8     0     0     3     4
# ->
by_cyl %>% summarise(head(across(), 2))
#> `summarise()` has grouped output by 'cyl'. You can override using the `.groups` argument.
#> # A tibble: 6 x 11
#> # Groups:   cyl [3]
#>     cyl   mpg  disp    hp  drat    wt  qsec    vs    am  gear  carb
#>   <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1     4  22.8  108     93  3.85  2.32  18.6     1     1     4     1
#> 2     4  24.4  147.    62  3.69  3.19  20       1     0     4     2
#> 3     6  21    160    110  3.9   2.62  16.5     0     1     4     4
#> 4     6  21    160    110  3.9   2.88  17.0     0     1     4     4
#> 5     8  18.7  360    175  3.15  3.44  17.0     0     0     3     2
#> 6     8  14.3  360    245  3.21  3.57  15.8     0     0     3     4
by_cyl %>% slice_head(n = 2)
#> # A tibble: 6 x 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  22.8     4  108     93  3.85  2.32  18.6     1     1     4     1
#> 2  24.4     4  147.    62  3.69  3.19  20       1     0     4     2
#> 3  21       6  160    110  3.9   2.62  16.5     0     1     4     4
#> 4  21       6  160    110  3.9   2.88  17.0     0     1     4     4
#> 5  18.7     8  360    175  3.15  3.44  17.0     0     0     3     2
#> 6  14.3     8  360    245  3.21  3.57  15.8     0     0     3     4

# Can refer to variables directly
by_cyl %>% do(mean = mean(.$vs))
#> # A tibble: 3 x 2
#> # Rowwise: 
#>     cyl mean     
#>   <dbl> <list>   
#> 1     4 <dbl [1]>
#> 2     6 <dbl [1]>
#> 3     8 <dbl [1]>
# ->
by_cyl %>% summarise(mean = mean(vs))
#> # A tibble: 3 x 2
#>     cyl  mean
#>   <dbl> <dbl>
#> 1     4 0.909
#> 2     6 0.571
#> 3     8 0    

# do() with named arguments becomes nest_by() + mutate() & list()
models <- by_cyl %>% do(mod = lm(mpg ~ disp, data = .))
# ->
models <- mtcars %>%
  nest_by(cyl) %>%
  mutate(mod = list(lm(mpg ~ disp, data = data)))
models %>% summarise(rsq = summary(mod)$r.squared)
#> `summarise()` has grouped output by 'cyl'. You can override using the `.groups` argument.
#> # A tibble: 3 x 2
#> # Groups:   cyl [3]
#>     cyl    rsq
#>   <dbl>  <dbl>
#> 1     4 0.648 
#> 2     6 0.0106
#> 3     8 0.270 

# use broom to turn models into data
models %>% do(data.frame(
  var = names(coef(.$mod)),
  coef(summary(.$mod)))
)
#> # A tibble: 6 x 5
#> # Rowwise: 
#>   var         Estimate Std..Error t.value   Pr...t..
#>   <chr>          <dbl>      <dbl>   <dbl>      <dbl>
#> 1 (Intercept) 40.9        3.59     11.4   0.00000120
#> 2 disp        -0.135      0.0332   -4.07  0.00278   
#> 3 (Intercept) 19.1        2.91      6.55  0.00124   
#> 4 disp         0.00361    0.0156    0.232 0.826     
#> 5 (Intercept) 22.0        3.35      6.59  0.0000259 
#> 6 disp        -0.0196     0.00932  -2.11  0.0568    
# ->
if (requireNamespace("broom")) {
  models %>% summarise(broom::tidy(mod))
}
#> Loading required namespace: broom
#> `summarise()` has grouped output by 'cyl'. You can override using the `.groups` argument.
#> # A tibble: 6 x 6
#> # Groups:   cyl [3]
#>     cyl term        estimate std.error statistic    p.value
#>   <dbl> <chr>          <dbl>     <dbl>     <dbl>      <dbl>
#> 1     4 (Intercept) 40.9       3.59       11.4   0.00000120
#> 2     4 disp        -0.135     0.0332     -4.07  0.00278   
#> 3     6 (Intercept) 19.1       2.91        6.55  0.00124   
#> 4     6 disp         0.00361   0.0156      0.232 0.826     
#> 5     8 (Intercept) 22.0       3.35        6.59  0.0000259 
#> 6     8 disp        -0.0196    0.00932    -2.11  0.0568