# S3 method for rvar
[[(x, i, ...)
# S3 method for rvar
[[(x, i, ...) <- value
# S3 method for rvar
[(x, ..., drop = FALSE)
# S3 method for rvar
[(x, i, ...) <- valueThe rvar slicing operators ([ and [[) attempt to implement the same
semantics as the base array slicing operators. There are some
exceptions; most notably, rvar slicing defaults to drop = FALSE instead
of drop = TRUE.
[[The [[ operator extracts (or replaces) single elements. It always
returns (or replaces) a scalar (length-1) rvar.
The x[[i,...]] operator can be used as follows:
x[[<numeric>]] for scalar numeric i: gives the ith element of x. If x is
multidimensional (i.e. length(dim(x)) > 1), extra dimensions are ignored
when indexing. For example, if x is a \(6 \times 2\) rvar array, the
7th element, x[[7]], will be the first element of the second column, x[1,2].
x[[<numeric rvar>]] for scalar numeric rvar i: a generalization of indexing when
i is a scalar numeric. Within each draw of x, selects the element
corresponding to the value of i within that same draw.
x[[<character>]] for scalar character i: gives the element of x with name
equal to i. Unlike with base arrays, does not work with
multidimensional rvars.
x[[i_1,i_2,...,i_n]] for scalar numeric or character i_1, i_2, etc.
Must provide exactly the same number of indices as dimensions in x. Selects
the element at the corresponding position in the rvar by number and/or
dimname (as a string).
[The [ operator extracts (or replaces) multiple elements. It always returns
(or replaces) a possibly-multidimensional rvar.
The x[i,...] operator can be used as follows:
x[<logical>] for vector logical i: i is recycled to the same length as x,
ignoring multiple dimensions in x, then an rvar vector is returned
containing the elements in x where i is TRUE.
x[<logical rvar>] for scalar logical rvar i: returns an rvar the same shape
as x containing only those draws where i is TRUE.
x[<numeric>] for vector numeric i: an rvar vector is returned
containing the ith elements of x, ignoring dimensions.
x[<matrix>] for numeric matrix i, where ncol(i) == length(dim(x)): each row
of i should give the multidimensional index for a single element in x. The
result is an rvar vector of length nrow(i) containing elements of x
selected by each row of i.
x[i_1,i_2,...,i_n] for vector numeric, character, or logical i_1,
i_2, etc. Returns a slice of x containing all elements from the dimensions
specified in i_1, i_2, etc. If an argument is left empty, all elements
from that dimension are included. Unlike base arrays, trailing dimensions
can be omitted entirely and will still be selected; for example, if x has
three dimensions, both x[1,,] and x[1,] can be used to create a
slice that includes all elements from the last two dimensions. Unlike base
arrays, [ defaults to drop = FALSE, so results retain the same number of
dimensions as x.
x <- rvar(array(1:24, dim = c(4,2,3)))
dimnames(x) <- list(c("a","b"), c("d","e","f"))
x
#> rvar<4>[2,3] mean ± sd:
#> d e f
#> a 2.5 ± 1.3 10.5 ± 1.3 18.5 ± 1.3
#> b 6.5 ± 1.3 14.5 ± 1.3 22.5 ± 1.3
## Slicing single elements
# x[[<numeric>]]
x[[2]]
#> rvar<4>[1] mean ± sd:
#> [1] 6.5 ± 1.3
# x[[<numeric rvar>]]
# notice the draws of x[1:4]...
draws_of(x[1:4])
#> [,1] [,2] [,3] [,4]
#> 1 1 5 9 13
#> 2 2 6 10 14
#> 3 3 7 11 15
#> 4 4 8 12 16
x[[rvar(c(1,3,4,4))]]
#> rvar<4>[1] mean ± sd:
#> [1] 10 ± 6.9
# ... x[[rvar(c(1,3,4,4))]] creates a mixures of those draws
draws_of(x[[rvar(c(1,3,4,4))]])
#> [,1]
#> 1 1
#> 2 10
#> 3 15
#> 4 16
# x[[i_1,i_2,...]]
x[[2,"e"]]
#> rvar<4>[1] mean ± sd:
#> [1] 14 ± 1.3
## Slicing multiple elements
# x[<logical>]
x[c(TRUE,TRUE,FALSE)]
#> rvar<4>[4] mean ± sd:
#> [1] 2.5 ± 1.3 6.5 ± 1.3 14.5 ± 1.3 18.5 ± 1.3
# x[<logical rvar>]
# select every other draw
x[rvar(c(TRUE,FALSE,TRUE,FALSE))]
#> rvar<2>[2,3] mean ± sd:
#> d e f
#> a 2 ± 1.4 10 ± 1.4 18 ± 1.4
#> b 6 ± 1.4 14 ± 1.4 22 ± 1.4
# x[<numeric>]
x[1:3]
#> rvar<4>[3] mean ± sd:
#> [1] 2.5 ± 1.3 6.5 ± 1.3 10.5 ± 1.3
# x[<matrix>]
x[rbind(
c(1,2),
c(1,3),
c(2,2)
)]
#> rvar<4>[3] mean ± sd:
#> [1] 10 ± 1.3 18 ± 1.3 14 ± 1.3
# x[i_1,i_2,...,i_n]
x[1,]
#> rvar<4>[1,3] mean ± sd:
#> d e f
#> a 2.5 ± 1.3 10.5 ± 1.3 18.5 ± 1.3
x[1,2:3]
#> rvar<4>[1,2] mean ± sd:
#> e f
#> a 10 ± 1.3 18 ± 1.3
x[,2:3]
#> rvar<4>[2,2] mean ± sd:
#> e f
#> a 10 ± 1.3 18 ± 1.3
#> b 14 ± 1.3 22 ± 1.3