Helpers for working with vectors

Generate vector subsets

Say we want to generate all subsets of a vector:

v <- 1:4
subsets(v)
#> [[1]]
#> [1] 1
#> 
#> [[2]]
#> [1] 2
#> 
#> [[3]]
#> [1] 3
#> 
#> [[4]]
#> [1] 4
#> 
#> [[5]]
#> [1] 1 2
#> 
#> [[6]]
#> [1] 1 3
#> 
#> [[7]]
#> [1] 1 4
#> 
#> [[8]]
#> [1] 2 3
#> 
#> [[9]]
#> [1] 2 4
#> 
#> [[10]]
#> [1] 3 4
#> 
#> [[11]]
#> [1] 1 2 3
#> 
#> [[12]]
#> [1] 1 2 4
#> 
#> [[13]]
#> [1] 1 3 4
#> 
#> [[14]]
#> [1] 2 3 4
#> 
#> [[15]]
#> [1] 1 2 3 4

It is also possible to only generate the subsets of, say, size 2 and 3:

v <- 1:4
subsets(v, n = 2:3)
#> [[1]]
#> [1] 1 2
#> 
#> [[2]]
#> [1] 1 3
#> 
#> [[3]]
#> [1] 1 4
#> 
#> [[4]]
#> [1] 2 3
#> 
#> [[5]]
#> [1] 2 4
#> 
#> [[6]]
#> [1] 3 4
#> 
#> [[7]]
#> [1] 1 2 3
#> 
#> [[8]]
#> [1] 1 2 4
#> 
#> [[9]]
#> [1] 1 3 4
#> 
#> [[10]]
#> [1] 2 3 4

Split vector into chunks

Say we want to split a vector into three chunks of equal size:

x <- 1:6
chunk_vector(x, n = 3)
#> $`1`
#> [1] 1 2
#> 
#> $`2`
#> [1] 3 4
#> 
#> $`3`
#> [1] 5 6

Alternatively, we can split x into chunks of size n = 3 by setting type = 2:

chunk_vector(x, n = 3, type = 2)
#> $`1`
#> [1] 1 2 3
#> 
#> $`2`
#> [1] 4 5 6

Both somehow also works if n is not a multiple of length(x):

x <- 1:7
chunk_vector(x, n = 3)
#> $`1`
#> [1] 1 2 3
#> 
#> $`2`
#> [1] 4 5
#> 
#> $`3`
#> [1] 6 7
chunk_vector(x, n = 3, type = 2)
#> $`1`
#> [1] 1 2 3
#> 
#> $`2`
#> [1] 4 5 6
#> 
#> $`3`
#> [1] 7

To prevent such “odd” cases, set strict = TRUE:

try(chunk_vector(1:7, n = 3, strict = TRUE))
#> Error in chunk_vector(1:7, n = 3, strict = TRUE) : 
#>   'n' is not a multiple of 'length(x)'