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Attribute checks - Dimensions existence and sizes

attributes-dimensions.Rd

Functions for the presence and number of dimensions and dimension names of an object.

  • n_dims() and n_dimnames() return the number of dimensions and dimension names, respectively, controlling for empty dimensions and invalid names.

  • has_dim(), has_dimnames(), and has_rownames() return whether the object has dimensions, dimension names, and rownames, respectively.

Usage

n_dims(x, empty = TRUE, how = "dim")

n_dimnames(x, invalid = TRUE, how = "dimnames")

has_dimnames(x, n = NULL, how = "dimnames")

has_rownames(x, how = "dimnames")

has_dim(x, n = NULL, how = "dim")

Arguments

x

[any] An object to test.

empty

[TRUE | FALSE] Whether to count empty dimensions and dimension names.

how

[character(1)] How to extract the attribute:

  • For dimensions: "dim" for dim() and "attr" for attr(x, "dim").

  • For dimension names: "dimnames" for dimnames() and "attr" for attr(x, "dimnames").

  • For rownames: "rownames" for rownames(), "dimnames" for the first element of dimnames(), and "attr" for attr(x, "row.names").

invalid

[TRUE | FALSE] Whether to count dimensions with NA, empty, or duplicate names.

n

[integer(1)] Number of dimensions to check for. Set to NULL to not test.

Value

  • [integer(1)] For n_dims() and n_dimnames().

  • [TRUE | FALSE] For has_dim(), has_dimnames(), and has_rownames(): the scalar result of the test.

Examples

x <- structure(
  1:6, dim = c(2, 3, 1),
  dimnames = list(c("a", "a"), c("x", "y", "z"), NULL)
)

# Counting dimensions and dimension names:
n_dims(x) #> 3
#> [1] 3
n_dims(x, empty = FALSE) #> 2
#> [1] 2

n_dimnames(x) #> 2
#> [1] 2
n_dimnames(x, invalid = FALSE) #> 1 (rownames have duplicates)
#> [1] 1

# Testing for dimensions and dimension names:
has_dimnames(x) #> TRUE
#> [1] TRUE
has_rownames(mtcars) #> TRUE
#> [1] TRUE
has_dim(mtcars) #> TRUE
#> [1] TRUE

# Data frames often have no actual dimension attribues:
has_dim(mtcars, how = "attr") #> FALSE
#> [1] FALSE
has_dimnames(mtcars, how = "attr") #> FALSE
#> [1] FALSE
has_rownames(mtcars, how = "row.names") #> TRUE (but have row.names one)
#> [1] TRUE