`slice_dt()` lets you index rows by their (integer) locations. It allows you to select, remove, and duplicate rows. It is accompanied by a number of helpers for common use cases:
* `slice_head_dt()` and `slice_tail_dt()` select the first or last rows. * `slice_sample_dt()` randomly selects rows. * `slice_min_dt()` and `slice_max_dt()` select rows with highest or lowest values of a variable.
slice_dt(.data, ..., by = NULL)
slice_head_dt(.data, n, by = NULL)
slice_tail_dt(.data, n, by = NULL)
slice_max_dt(.data, order_by, n, by = NULL, with_ties = TRUE)
slice_min_dt(.data, order_by, n, by = NULL, with_ties = TRUE)
slice_sample_dt(.data, n, replace = FALSE, by = NULL)A data.table
Provide either positive values to keep, or negative values to drop. The values provided must be either all positive or all negative.
Slice by which group(s)?
When larger than or equal to 1, the number of rows. When between 0 and 1, the proportion of rows to select.
Variable or function of variables to order by.
Should ties be kept together? The default, `TRUE`, may return more rows than you request. Use `FALSE` to ignore ties, and return the first `n` rows.
Should sampling be performed with (`TRUE`) or without (`FALSE`, the default) replacement.
A data.table
a = iris
slice_dt(a,1,2)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.1 3.5 1.4 0.2 setosa
#> 2: 4.9 3.0 1.4 0.2 setosa
slice_dt(a,2:3)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 4.9 3.0 1.4 0.2 setosa
#> 2: 4.7 3.2 1.3 0.2 setosa
slice_dt(a,141:.N)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 6.7 3.1 5.6 2.4 virginica
#> 2: 6.9 3.1 5.1 2.3 virginica
#> 3: 5.8 2.7 5.1 1.9 virginica
#> 4: 6.8 3.2 5.9 2.3 virginica
#> 5: 6.7 3.3 5.7 2.5 virginica
#> 6: 6.7 3.0 5.2 2.3 virginica
#> 7: 6.3 2.5 5.0 1.9 virginica
#> 8: 6.5 3.0 5.2 2.0 virginica
#> 9: 6.2 3.4 5.4 2.3 virginica
#> 10: 5.9 3.0 5.1 1.8 virginica
slice_dt(a,1,.N)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.1 3.5 1.4 0.2 setosa
#> 2: 5.9 3.0 5.1 1.8 virginica
slice_head_dt(a,5)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.1 3.5 1.4 0.2 setosa
#> 2: 4.9 3.0 1.4 0.2 setosa
#> 3: 4.7 3.2 1.3 0.2 setosa
#> 4: 4.6 3.1 1.5 0.2 setosa
#> 5: 5.0 3.6 1.4 0.2 setosa
slice_head_dt(a,0.1)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.1 3.5 1.4 0.2 setosa
#> 2: 4.9 3.0 1.4 0.2 setosa
#> 3: 4.7 3.2 1.3 0.2 setosa
#> 4: 4.6 3.1 1.5 0.2 setosa
#> 5: 5.0 3.6 1.4 0.2 setosa
#> 6: 5.4 3.9 1.7 0.4 setosa
#> 7: 4.6 3.4 1.4 0.3 setosa
#> 8: 5.0 3.4 1.5 0.2 setosa
#> 9: 4.4 2.9 1.4 0.2 setosa
#> 10: 4.9 3.1 1.5 0.1 setosa
#> 11: 5.4 3.7 1.5 0.2 setosa
#> 12: 4.8 3.4 1.6 0.2 setosa
#> 13: 4.8 3.0 1.4 0.1 setosa
#> 14: 4.3 3.0 1.1 0.1 setosa
#> 15: 5.8 4.0 1.2 0.2 setosa
slice_tail_dt(a,5)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 6.7 3.0 5.2 2.3 virginica
#> 2: 6.3 2.5 5.0 1.9 virginica
#> 3: 6.5 3.0 5.2 2.0 virginica
#> 4: 6.2 3.4 5.4 2.3 virginica
#> 5: 5.9 3.0 5.1 1.8 virginica
slice_tail_dt(a,0.1)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 7.7 3.0 6.1 2.3 virginica
#> 2: 6.3 3.4 5.6 2.4 virginica
#> 3: 6.4 3.1 5.5 1.8 virginica
#> 4: 6.0 3.0 4.8 1.8 virginica
#> 5: 6.9 3.1 5.4 2.1 virginica
#> 6: 6.7 3.1 5.6 2.4 virginica
#> 7: 6.9 3.1 5.1 2.3 virginica
#> 8: 5.8 2.7 5.1 1.9 virginica
#> 9: 6.8 3.2 5.9 2.3 virginica
#> 10: 6.7 3.3 5.7 2.5 virginica
#> 11: 6.7 3.0 5.2 2.3 virginica
#> 12: 6.3 2.5 5.0 1.9 virginica
#> 13: 6.5 3.0 5.2 2.0 virginica
#> 14: 6.2 3.4 5.4 2.3 virginica
#> 15: 5.9 3.0 5.1 1.8 virginica
slice_max_dt(a,Sepal.Length,10)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 7.9 3.8 6.4 2.0 virginica
#> 2: 7.7 3.8 6.7 2.2 virginica
#> 3: 7.7 2.6 6.9 2.3 virginica
#> 4: 7.7 2.8 6.7 2.0 virginica
#> 5: 7.7 3.0 6.1 2.3 virginica
#> 6: 7.6 3.0 6.6 2.1 virginica
#> 7: 7.4 2.8 6.1 1.9 virginica
#> 8: 7.3 2.9 6.3 1.8 virginica
#> 9: 7.2 3.6 6.1 2.5 virginica
#> 10: 7.2 3.2 6.0 1.8 virginica
#> 11: 7.2 3.0 5.8 1.6 virginica
slice_max_dt(a,Sepal.Length,10,with_ties = FALSE)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 7.9 3.8 6.4 2.0 virginica
#> 2: 7.7 3.8 6.7 2.2 virginica
#> 3: 7.7 2.6 6.9 2.3 virginica
#> 4: 7.7 2.8 6.7 2.0 virginica
#> 5: 7.7 3.0 6.1 2.3 virginica
#> 6: 7.6 3.0 6.6 2.1 virginica
#> 7: 7.4 2.8 6.1 1.9 virginica
#> 8: 7.3 2.9 6.3 1.8 virginica
#> 9: 7.2 3.6 6.1 2.5 virginica
#> 10: 7.2 3.2 6.0 1.8 virginica
slice_min_dt(a,Sepal.Length,10)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 4.3 3.0 1.1 0.1 setosa
#> 2: 4.4 2.9 1.4 0.2 setosa
#> 3: 4.4 3.0 1.3 0.2 setosa
#> 4: 4.4 3.2 1.3 0.2 setosa
#> 5: 4.5 2.3 1.3 0.3 setosa
#> 6: 4.6 3.1 1.5 0.2 setosa
#> 7: 4.6 3.4 1.4 0.3 setosa
#> 8: 4.6 3.6 1.0 0.2 setosa
#> 9: 4.6 3.2 1.4 0.2 setosa
#> 10: 4.7 3.2 1.3 0.2 setosa
#> 11: 4.7 3.2 1.6 0.2 setosa
slice_min_dt(a,Sepal.Length,10,with_ties = FALSE)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 4.3 3.0 1.1 0.1 setosa
#> 2: 4.4 2.9 1.4 0.2 setosa
#> 3: 4.4 3.0 1.3 0.2 setosa
#> 4: 4.4 3.2 1.3 0.2 setosa
#> 5: 4.5 2.3 1.3 0.3 setosa
#> 6: 4.6 3.1 1.5 0.2 setosa
#> 7: 4.6 3.4 1.4 0.3 setosa
#> 8: 4.6 3.6 1.0 0.2 setosa
#> 9: 4.6 3.2 1.4 0.2 setosa
#> 10: 4.7 3.2 1.3 0.2 setosa
slice_sample_dt(a,10)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 5.8 2.8 5.1 2.4 virginica
#> 2: 5.8 2.7 3.9 1.2 versicolor
#> 3: 5.1 3.8 1.5 0.3 setosa
#> 4: 5.4 3.0 4.5 1.5 versicolor
#> 5: 6.7 2.5 5.8 1.8 virginica
#> 6: 6.5 3.2 5.1 2.0 virginica
#> 7: 5.4 3.9 1.3 0.4 setosa
#> 8: 6.3 2.5 4.9 1.5 versicolor
#> 9: 5.5 4.2 1.4 0.2 setosa
#> 10: 4.6 3.2 1.4 0.2 setosa
slice_sample_dt(a,0.1)
#> Sepal.Length Sepal.Width Petal.Length Petal.Width Species
#> <num> <num> <num> <num> <fctr>
#> 1: 6.7 3.0 5.0 1.7 versicolor
#> 2: 4.9 3.1 1.5 0.1 setosa
#> 3: 5.0 3.4 1.5 0.2 setosa
#> 4: 5.2 3.4 1.4 0.2 setosa
#> 5: 6.0 2.2 5.0 1.5 virginica
#> 6: 5.2 4.1 1.5 0.1 setosa
#> 7: 7.2 3.0 5.8 1.6 virginica
#> 8: 5.4 3.0 4.5 1.5 versicolor
#> 9: 5.8 2.6 4.0 1.2 versicolor
#> 10: 5.8 4.0 1.2 0.2 setosa
#> 11: 5.4 3.4 1.7 0.2 setosa
#> 12: 4.5 2.3 1.3 0.3 setosa
#> 13: 5.5 2.6 4.4 1.2 versicolor
#> 14: 6.0 2.9 4.5 1.5 versicolor
#> 15: 6.9 3.1 5.1 2.3 virginica
# use by to slice by group
## following codes get the same results
slice_dt(a,1:3,by = "Species")
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.1 3.5 1.4 0.2
#> 2: setosa 4.9 3.0 1.4 0.2
#> 3: setosa 4.7 3.2 1.3 0.2
#> 4: versicolor 7.0 3.2 4.7 1.4
#> 5: versicolor 6.4 3.2 4.5 1.5
#> 6: versicolor 6.9 3.1 4.9 1.5
#> 7: virginica 6.3 3.3 6.0 2.5
#> 8: virginica 5.8 2.7 5.1 1.9
#> 9: virginica 7.1 3.0 5.9 2.1
slice_dt(a,1:3,by = Species)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.1 3.5 1.4 0.2
#> 2: setosa 4.9 3.0 1.4 0.2
#> 3: setosa 4.7 3.2 1.3 0.2
#> 4: versicolor 7.0 3.2 4.7 1.4
#> 5: versicolor 6.4 3.2 4.5 1.5
#> 6: versicolor 6.9 3.1 4.9 1.5
#> 7: virginica 6.3 3.3 6.0 2.5
#> 8: virginica 5.8 2.7 5.1 1.9
#> 9: virginica 7.1 3.0 5.9 2.1
slice_dt(a,1:3,by = .(Species))
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.1 3.5 1.4 0.2
#> 2: setosa 4.9 3.0 1.4 0.2
#> 3: setosa 4.7 3.2 1.3 0.2
#> 4: versicolor 7.0 3.2 4.7 1.4
#> 5: versicolor 6.4 3.2 4.5 1.5
#> 6: versicolor 6.9 3.1 4.9 1.5
#> 7: virginica 6.3 3.3 6.0 2.5
#> 8: virginica 5.8 2.7 5.1 1.9
#> 9: virginica 7.1 3.0 5.9 2.1
slice_head_dt(a,2,by = Species)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.1 3.5 1.4 0.2
#> 2: setosa 4.9 3.0 1.4 0.2
#> 3: versicolor 7.0 3.2 4.7 1.4
#> 4: versicolor 6.4 3.2 4.5 1.5
#> 5: virginica 6.3 3.3 6.0 2.5
#> 6: virginica 5.8 2.7 5.1 1.9
slice_tail_dt(a,2,by = Species)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.3 3.7 1.5 0.2
#> 2: setosa 5.0 3.3 1.4 0.2
#> 3: versicolor 5.1 2.5 3.0 1.1
#> 4: versicolor 5.7 2.8 4.1 1.3
#> 5: virginica 6.2 3.4 5.4 2.3
#> 6: virginica 5.9 3.0 5.1 1.8
slice_max_dt(a,Sepal.Length,3,by = Species)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.8 4.0 1.2 0.2
#> 2: setosa 5.7 4.4 1.5 0.4
#> 3: setosa 5.7 3.8 1.7 0.3
#> 4: versicolor 7.0 3.2 4.7 1.4
#> 5: versicolor 6.9 3.1 4.9 1.5
#> 6: versicolor 6.8 2.8 4.8 1.4
#> 7: virginica 7.7 3.8 6.7 2.2
#> 8: virginica 7.7 2.6 6.9 2.3
#> 9: virginica 7.7 2.8 6.7 2.0
#> 10: virginica 7.9 3.8 6.4 2.0
#> 11: virginica 7.7 3.0 6.1 2.3
slice_max_dt(a,Sepal.Length,3,by = Species,with_ties = FALSE)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.8 4.0 1.2 0.2
#> 2: setosa 5.7 4.4 1.5 0.4
#> 3: setosa 5.7 3.8 1.7 0.3
#> 4: versicolor 7.0 3.2 4.7 1.4
#> 5: versicolor 6.9 3.1 4.9 1.5
#> 6: versicolor 6.8 2.8 4.8 1.4
#> 7: virginica 7.7 3.8 6.7 2.2
#> 8: virginica 7.7 2.6 6.9 2.3
#> 9: virginica 7.9 3.8 6.4 2.0
slice_min_dt(a,Sepal.Length,3,by = Species)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 4.4 2.9 1.4 0.2
#> 2: setosa 4.3 3.0 1.1 0.1
#> 3: setosa 4.4 3.0 1.3 0.2
#> 4: setosa 4.4 3.2 1.3 0.2
#> 5: versicolor 4.9 2.4 3.3 1.0
#> 6: versicolor 5.0 2.0 3.5 1.0
#> 7: versicolor 5.0 2.3 3.3 1.0
#> 8: virginica 4.9 2.5 4.5 1.7
#> 9: virginica 5.7 2.5 5.0 2.0
#> 10: virginica 5.6 2.8 4.9 2.0
slice_min_dt(a,Sepal.Length,3,by = Species,with_ties = FALSE)
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 4.4 2.9 1.4 0.2
#> 2: setosa 4.3 3.0 1.1 0.1
#> 3: setosa 4.4 3.0 1.3 0.2
#> 4: versicolor 4.9 2.4 3.3 1.0
#> 5: versicolor 5.0 2.0 3.5 1.0
#> 6: versicolor 5.0 2.3 3.3 1.0
#> 7: virginica 4.9 2.5 4.5 1.7
#> 8: virginica 5.7 2.5 5.0 2.0
#> 9: virginica 5.6 2.8 4.9 2.0
# in `slice_sample_dt`, "by" could only take character class
slice_sample_dt(a,.1,by = "Species")
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 4.6 3.6 1.0 0.2
#> 2: setosa 4.4 3.0 1.3 0.2
#> 3: setosa 4.9 3.6 1.4 0.1
#> 4: setosa 5.1 3.5 1.4 0.2
#> 5: setosa 4.6 3.2 1.4 0.2
#> 6: setosa 4.8 3.4 1.6 0.2
#> 7: setosa 5.5 3.5 1.3 0.2
#> 8: setosa 4.6 3.1 1.5 0.2
#> 9: setosa 4.8 3.0 1.4 0.1
#> 10: setosa 4.4 3.2 1.3 0.2
#> 11: setosa 5.1 3.8 1.6 0.2
#> 12: setosa 5.1 3.8 1.5 0.3
#> 13: setosa 5.5 4.2 1.4 0.2
#> 14: setosa 4.8 3.1 1.6 0.2
#> 15: setosa 5.0 3.5 1.6 0.6
#> 16: versicolor 6.0 2.7 5.1 1.6
#> 17: versicolor 5.6 2.7 4.2 1.3
#> 18: versicolor 5.5 2.3 4.0 1.3
#> 19: versicolor 6.6 2.9 4.6 1.3
#> 20: versicolor 5.9 3.0 4.2 1.5
#> 21: versicolor 6.0 3.4 4.5 1.6
#> 22: versicolor 5.7 3.0 4.2 1.2
#> 23: versicolor 5.5 2.6 4.4 1.2
#> 24: versicolor 5.1 2.5 3.0 1.1
#> 25: versicolor 5.5 2.4 3.8 1.1
#> 26: versicolor 5.7 2.9 4.2 1.3
#> 27: versicolor 5.0 2.0 3.5 1.0
#> 28: versicolor 6.1 2.8 4.0 1.3
#> 29: versicolor 5.2 2.7 3.9 1.4
#> 30: versicolor 6.1 3.0 4.6 1.4
#> 31: virginica 6.0 3.0 4.8 1.8
#> 32: virginica 6.4 2.8 5.6 2.1
#> 33: virginica 6.1 2.6 5.6 1.4
#> 34: virginica 5.9 3.0 5.1 1.8
#> 35: virginica 7.6 3.0 6.6 2.1
#> 36: virginica 6.1 3.0 4.9 1.8
#> 37: virginica 5.8 2.7 5.1 1.9
#> 38: virginica 6.3 2.5 5.0 1.9
#> 39: virginica 6.4 3.1 5.5 1.8
#> 40: virginica 6.7 3.3 5.7 2.1
#> 41: virginica 7.7 3.0 6.1 2.3
#> 42: virginica 6.8 3.2 5.9 2.3
#> 43: virginica 7.9 3.8 6.4 2.0
#> 44: virginica 7.2 3.0 5.8 1.6
#> 45: virginica 6.9 3.1 5.4 2.1
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
slice_sample_dt(a,3,by = "Species")
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 5.1 3.8 1.5 0.3
#> 2: setosa 5.0 3.5 1.3 0.3
#> 3: setosa 5.4 3.9 1.7 0.4
#> 4: versicolor 5.6 2.7 4.2 1.3
#> 5: versicolor 6.2 2.2 4.5 1.5
#> 6: versicolor 4.9 2.4 3.3 1.0
#> 7: virginica 6.7 3.0 5.2 2.3
#> 8: virginica 7.7 3.0 6.1 2.3
#> 9: virginica 6.3 2.5 5.0 1.9
slice_sample_dt(a,51,replace = TRUE,by = "Species")
#> Species Sepal.Length Sepal.Width Petal.Length Petal.Width
#> <fctr> <num> <num> <num> <num>
#> 1: setosa 4.7 3.2 1.3 0.2
#> 2: setosa 4.8 3.0 1.4 0.1
#> 3: setosa 4.3 3.0 1.1 0.1
#> 4: setosa 4.4 2.9 1.4 0.2
#> 5: setosa 4.8 3.4 1.6 0.2
#> ---
#> 149: virginica 7.2 3.2 6.0 1.8
#> 150: virginica 6.3 3.3 6.0 2.5
#> 151: virginica 6.3 2.8 5.1 1.5
#> 152: virginica 7.2 3.2 6.0 1.8
#> 153: virginica 5.8 2.7 5.1 1.9