R: Extract feature-level meta

wk_meta {wk} | R Documentation

## Extract feature-level meta

### Description

These functions return the non-coordinate information of a geometry and/or vector. They do not parse an entire geometry/vector and are intended to be very fast even for large vectors.

### Usage

    wk_meta(handleable, ...)

    ## Default S3 method:
    wk_meta(handleable, ...)

    wk_vector_meta(handleable, ...)

    ## Default S3 method:
    wk_vector_meta(handleable, ...)

    wk_meta_handler()

    wk_vector_meta_handler()

    wk_geometry_type_label(geometry_type)

    wk_geometry_type(geometry_type_label)

### Arguments

`handleable` | A geometry vector (e.g., `wkb()`, `wkt()`, `xy()`, `rct()`, or `sf::st_sfc()`) for which `wk_handle()` is defined.
`...` | Passed to the `wk_handle()` method.
`geometry_type` | An integer code for the geometry type. These integers follow the WKB specification (e.g., 1 for point, 7 for geometrycollection).
`geometry_type_label` | A character vector of (lowercase) geometry type labels as would be found in WKT (e.g., point, geometrycollection).

### Value

A data.frame with columns:

- `geometry_type`: An integer identifying the geometry type. A value of 0 indicates that the types of geometry in the vector are not known without parsing the entire vector.

- `size`: For points and linestrings, the number of coordinates; for polygons, the number of rings; for collections, the number of child geometries. A value of zero indicates an EMPTY geometry. A value of `NA` means this value is unknown without parsing the entire geometry.

- `has_z`: `TRUE` if coordinates contain a Z value. A value of `NA` means this value is unknown without parsing the entire vector.

- `has_m`: `TRUE` if coordinates contain an M value. A value of `NA` means this value is unknown without parsing the entire vector.

- `srid`: An integer identifying a CRS or NA if this value was not provided.

- `precision`: A grid size or 0.0 if a grid size was not provided. Note that coordinate values may not have been rounded; the grid size only refers to the level of detail with which they should be interpreted.

### Examples

    wk_vector_meta(as_wkt("LINESTRING (0 0, 1 1)"))
    wk_meta(as_wkt("LINESTRING (0 0, 1 1)"))
    wk_meta(as_wkb("LINESTRING (0 0, 1 1)"))

    wk_geometry_type_label(1:7)
    wk_geometry_type(c("point", "geometrycollection"))

[Package wk version 0.4.0 Index]