Derived accessors for tmap source metadata

Convenience functions to extract specific parts of the metadata object returned by tmap_src_meta.

Usage

tmap_src_layers(meta)

tmap_src_vars(meta, layer = NULL)

tmap_src_cats(meta, layer = NULL, var)

Arguments

meta

List. Output of tmap_src_meta.

layer

Character. Layer name. May be omitted when the source has exactly one layer; required otherwise.

var

Character. Variable name within the layer.

Value

tmap_src_layers

Character vector of layer names.

tmap_src_vars

Data frame with columns variable, class, categories (list-column), and palette (list-column) for all variables in the layer.

tmap_src_cats

A list with elements categories (character vector of known category values) and palette (named character vector of hex colours), both NULL when no catalogue entry exists for layer.var.

Examples

if (FALSE) { # \dontrun{
urls <- tmap_src_overture()
meta <- tmap_src_meta(urls$buildings)

tmap_src_layers(meta)
#> [1] "building" "building_part"

tmap_src_vars(meta, layer = "building")

tmap_src_cats(meta, layer = "building", var = "subtype")
#> $categories
#>  [1] "residential" "commercial" ...
#> $palette
#>  residential  commercial ...
#>  "#f4a460"    "#4169e1"  ...
} # }