Create a batch indicator for splitting an object

A generic function to create an indicator for splitting an object into n batches, or batches of a given size. The data.frame method batches rows.

Usage

batch(x, n = NULL, size = NULL, ..., balance = !is.null(n))

# S3 method for data.frame
batch(x, n = NULL, size = NULL, ..., balance = !is.null(n))

Arguments

x: A vector or data frame.
n: An integer. The number of batches to create.
size: An integer. The size of batches to create.
...: Arguments passed on to further methods.
balance: Logical. Should batch sizes be (approximately) balanced?

Value

An integer vector suitable to use as an index to split() the object by.

Examples

batch(LETTERS, 8)
#>  [1] 1 1 1 1 2 2 2 2 3 3 3 4 4 4 5 5 5 6 6 6 7 7 7 8 8 8
batch(LETTERS, size = 8)
#>  [1] 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 4 4
batch(LETTERS, size = 8, balance = TRUE)
#>  [1] 1 1 1 1 1 1 1 2 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4

# The data.frame method batches rows
split(iris, batch(iris, 2)) |> str()
#> List of 2
#>  $ 1:'data.frame':	75 obs. of  5 variables:
#>   ..$ Sepal.Length: num [1:75] 5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
#>   ..$ Sepal.Width : num [1:75] 3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
#>   ..$ Petal.Length: num [1:75] 1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
#>   ..$ Petal.Width : num [1:75] 0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
#>   ..$ Species     : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ...
#>  $ 2:'data.frame':	75 obs. of  5 variables:
#>   ..$ Sepal.Length: num [1:75] 6.6 6.8 6.7 6 5.7 5.5 5.5 5.8 6 5.4 ...
#>   ..$ Sepal.Width : num [1:75] 3 2.8 3 2.9 2.6 2.4 2.4 2.7 2.7 3 ...
#>   ..$ Petal.Length: num [1:75] 4.4 4.8 5 4.5 3.5 3.8 3.7 3.9 5.1 4.5 ...
#>   ..$ Petal.Width : num [1:75] 1.4 1.4 1.7 1.5 1 1.1 1 1.2 1.6 1.5 ...
#>   ..$ Species     : Factor w/ 3 levels "setosa","versicolor",..: 2 2 2 2 2 2 2 2 2 2 ...