Extract array of a single (possibly indexed) variable

Extract an array of draws of a single variable, including any dimensions of variables with indices.

Usage

extract_variable_array(x, variable, with_chains = TRUE, ...)

# Default S3 method
extract_variable_array(x, variable, with_chains = TRUE, ...)

# S3 method for class 'draws'
extract_variable_array(x, variable, with_chains = TRUE, ...)

Arguments

x

(draws) A draws object or another R object for which the method is defined.

variable

(string) The name of the variable to extract. To extract all dimensions from variables with indices (e.g. "x[1]"), provide the base variable name (e.g. "x").

with_chains

(logical) Should the array of draws include a dimension for chains? If TRUE (the default), chains are included and the array has dimension c(niterations(x), nchains(x), ...). If FALSE, chains are not included and the array has dimension c(niterations(x) * nchains(x), ...).

...

Arguments passed to individual methods (if applicable).

Value

An array with dimension niterations(x) x nchains(x) x any remaining dimensions determined by the indices of the variable x (if with_chains = TRUE) or dimension niterations(x) * nchains(x) x any remaining dimensions (if with_chains = FALSE).

See also

Other variable extraction methods: extract_list_of_variable_arrays(), extract_variable(), extract_variable_matrix()

Examples

x <- example_draws(example = "multi_normal")

mu <- extract_variable_array(x, variable = "mu")
str(mu)
#>  num [1:100, 1:4, 1:3] 0.18119 -0.03419 -0.05875 -0.1536 0.00989 ...
#>  - attr(*, "dimnames")=List of 3
#>   ..$ : NULL
#>   ..$ : NULL
#>   ..$ : NULL

# With chains collapsed
mu_no_chains <- extract_variable_array(x, variable = "mu", with_chains = FALSE)
str(mu_no_chains)
#>  num [1:400, 1:3] 0.18119 -0.03419 -0.05875 -0.1536 0.00989 ...
#>  - attr(*, "dimnames")=List of 2
#>   ..$ : chr [1:400] "1" "2" "3" "4" ...
#>   ..$ : NULL

mu1 <- extract_variable_array(x, variable = "mu[1]")
str(mu1)
#>  num [1:100, 1:4, 1] 0.18119 -0.03419 -0.05875 -0.1536 0.00989 ...
#>  - attr(*, "dimnames")=List of 3
#>   ..$ : NULL
#>   ..$ : NULL
#>   ..$ : NULL

Sigma <- extract_variable_array(x, variable = "Sigma")
str(Sigma)
#>  num [1:100, 1:4, 1:3, 1:3] 1.2 1.14 1.12 1.14 1.19 ...
#>  - attr(*, "dimnames")=List of 4
#>   ..$ : NULL
#>   ..$ : NULL
#>   ..$ : NULL
#>   ..$ : NULL