oe_get_keys: Return all keys stored in "other_tags" column

Description

This function is used to return the names of all keys that are stored in "other_tags" column since they were not explicitly included in the file. See Details.

Usage

oe_get_keys(zone, layer = "lines")
# S3 method for default
oe_get_keys(zone, layer = "lines")
# S3 method for character
oe_get_keys(zone, layer = "lines")
# S3 method for sf
oe_get_keys(zone, layer = "lines")

Arguments

zone

An sf object (typically read-in with oe_read() or oe_get()) with an other_tags field, or a character vector (of length 1) that points to a .gpkg file (typically created using oe_vectortranslate() or oe_get()).

layer

Which layer should be read in? Typically points, lines (the default), multilinestrings, multipolygons or other_relations. If you specify an ad-hoc query using the argument query (see introductory vignette and examples), then oe_get() and oe_read() will read the layer specified in the query and ignore layer. See also #122.

Value

A character vector indicating the name of all keys stored in "other_tags" field.

Details

OSM data are typically documented using several tags. A tag is a pair of two items, namely a key and a value. As we documented in oe_vectortranslate(), the conversion between .osm.pbf and .gpkg formats is governed by a CONFIG file that indicates which tags are explicitly added to the .gpkg file. All the other keys stored in the .osm.pbf file are automatically appended using an "other_tags" field, with a syntax compatible with the PostgreSQL HSTORE type. This function is used to display the names of all keys stored in the "other_tags" column.

You can also use the hstore_get_value() function from GDAL to extract one particular tag from an existing .gpkg file. Check the introductory vignette and see examples.

The definition of a generic S3 implementation started in osmextract/issues/138.

Examples

Run this code

# NOT RUN {
itsleeds_gpkg_path = oe_get("ITS Leeds", download_only = TRUE)
oe_get_keys(itsleeds_gpkg_path)

itsleeds = oe_get("ITS Leeds")
oe_get_keys(itsleeds)

# Add an extra key to an existing .gpkg file without vectortranslate
names(oe_read(
  itsleeds_gpkg_path,
  query = "SELECT *,  hstore_get_value(other_tags, 'oneway')  AS oneway FROM lines"
))
# }