Create one or more scalar variables summarizing the variables of an existing data.table.
summarise(.data, ..., by = NULL)
summarise_when(.data, when, ..., by = NULL)
summarise_vars(.data, .cols = NULL, .func, ..., by)A data.table
List of variables or name-value pairs of summary/modifications
functions for summarise_dt.Additional parameters to be passed to
parameter '.func' in summarise_vars.
Unquoted name of grouping variable of list of unquoted names of grouping variables. For details see data.table
An object which can be coerced to logical mode
Columns to be summarised.
Function to be run within each column, should return a value or vectors with same length.
A data.table
a = as.data.table(iris)
a %>% summarise(sum = sum(Sepal.Length),avg = mean(Sepal.Length))
#> sum avg
#> <num> <num>
#> 1: 876.5 5.843333
a %>%
summarise_when(Sepal.Length > 5, avg = mean(Sepal.Length), by = Species)
#> Species avg
#> <fctr> <num>
#> 1: setosa 5.313636
#> 2: versicolor 5.997872
#> 3: virginica 6.622449
a %>%
summarise_vars(is.numeric, min, by = Species)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 4.3 2.3 1.0 0.1
#> 2: versicolor 4.9 2.0 3.0 1.0
#> 3: virginica 4.9 2.2 4.5 1.4