Adds or updates columns in data.frame.
mutate_dt(.data, ..., by)
transmute_dt(.data, ..., by)data.table
iris %>% mutate_dt(one = 1,Sepal.Length = Sepal.Length + 1)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species one
#> <num> <num> <num> <num> <fctr> <num>
#> 1: 6.1 3.5 1.4 0.2 setosa 1
#> 2: 5.9 3.0 1.4 0.2 setosa 1
#> 3: 5.7 3.2 1.3 0.2 setosa 1
#> 4: 5.6 3.1 1.5 0.2 setosa 1
#> 5: 6.0 3.6 1.4 0.2 setosa 1
#> ---
#> 146: 7.7 3.0 5.2 2.3 virginica 1
#> 147: 7.3 2.5 5.0 1.9 virginica 1
#> 148: 7.5 3.0 5.2 2.0 virginica 1
#> 149: 7.2 3.4 5.4 2.3 virginica 1
#> 150: 6.9 3.0 5.1 1.8 virginica 1
iris %>% transmute_dt(one = 1,Sepal.Length = Sepal.Length + 1)
#> one Sepal.Length
#> <num> <num>
#> 1: 1 6.1
#> 2: 1 5.9
#> 3: 1 5.7
#> 4: 1 5.6
#> 5: 1 6.0
#> ---
#> 146: 1 7.7
#> 147: 1 7.3
#> 148: 1 7.5
#> 149: 1 7.2
#> 150: 1 6.9
# add group number with symbol `.GRP`
iris %>% mutate_dt(id = 1:.N,grp = .GRP,by = Species)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species id grp
#> <num> <num> <num> <num> <fctr> <int> <int>
#> 1: 5.1 3.5 1.4 0.2 setosa 1 1
#> 2: 4.9 3.0 1.4 0.2 setosa 2 1
#> 3: 4.7 3.2 1.3 0.2 setosa 3 1
#> 4: 4.6 3.1 1.5 0.2 setosa 4 1
#> 5: 5.0 3.6 1.4 0.2 setosa 5 1
#> ---
#> 146: 6.7 3.0 5.2 2.3 virginica 46 3
#> 147: 6.3 2.5 5.0 1.9 virginica 47 3
#> 148: 6.5 3.0 5.2 2.0 virginica 48 3
#> 149: 6.2 3.4 5.4 2.3 virginica 49 3
#> 150: 5.9 3.0 5.1 1.8 virginica 50 3