Summarise columns to single values

Source: R/summarise_dt.R

Analogous function for summarise in dplyr.

summarise_dt(data, ..., by = NULL)

summarize_dt(data, ..., by = NULL)

Arguments

data

data.frame
...

List of variables or name-value pairs of summary/modifications functions.
by

unquoted name of grouping variable of list of unquoted names of grouping variables. For details see data.table

Value

data.table

See also

summarise

Examples

iris %>% summarise_dt(avg = mean(Sepal.Length))
#>         avg
#> 1: 5.843333
iris %>% summarise_dt(avg = mean(Sepal.Length),by = Species)
#>       Species   avg
#> 1:     setosa 5.006
#> 2: versicolor 5.936
#> 3:  virginica 6.588
mtcars %>% summarise_dt(avg = mean(hp),by = .(cyl,vs))
#>    cyl vs      avg
#> 1:   6  0 131.6667
#> 2:   4  1  81.8000
#> 3:   6  1 115.2500
#> 4:   8  0 209.2143
#> 5:   4  0  91.0000

# the data.table way
mtcars %>% summarise_dt(cyl_n = .N, by = .(cyl, vs)) # `.`` is short for list
#>    cyl vs cyl_n
#> 1:   6  0     3
#> 2:   4  1    10
#> 3:   6  1     4
#> 4:   8  0    14
#> 5:   4  0     1