Returns the values available for each facetted field, together with the number of records carrying them. This is a quick way to discover what a field actually contains before writing a `where` clause or a `refine` filter for [get_cov_data()].
The portal returns only the most common values of each facet (currently the top 100). Use [aggregate_cov_data()] with a `group_by` for an exhaustive count.
Results are cached for the duration of the R session.
Usage
get_cov_facets(
dataset_id,
facet = NULL,
where = NULL,
refine = NULL,
exclude = NULL,
apikey = getOption("VancouverOpenDataApiKey"),
refresh = FALSE
)Arguments
- dataset_id
the CoV open data dataset id
- facet
Name(s) of the fields to facet on. Default `NULL` returns every facetted field in the dataset.
- where
Filter expression using ODSQL syntax, restricting the records the counts are computed over. Default `NULL`.
- refine
Facet filter(s) of the form `"field:value"`; see [get_cov_data()]. Default `NULL`.
- exclude
Facet exclusion(s) of the form `"field:value"`. Default `NULL`.
- apikey
the CoV open data API key, optional
- refresh
Bypass the session cache and re-download, default `FALSE`
Value
A tibble with columns `facet` (the field name), `value`, and `count`. Returns `NULL` with a warning if the API cannot be reached.
See also
[get_cov_metadata()] for the list of fields, [list_cov_facets()] for the facets of the catalogue itself, [aggregate_cov_data()] for complete server-side counts
Examples
# \donttest{
# What values does the genus field take?
get_cov_facets("public-trees", facet = "genus_name")
#> # A tibble: 100 × 3
#> facet value count
#> <chr> <chr> <int>
#> 1 genus_name ACER 42180
#> 2 genus_name PRUNUS 30238
#> 3 genus_name QUERCUS 8970
#> 4 genus_name FRAXINUS 8026
#> 5 genus_name TILIA 6785
#> 6 genus_name CARPINUS 6750
#> 7 genus_name THUJA 6215
#> 8 genus_name FAGUS 6186
#> 9 genus_name MAGNOLIA 4705
#> 10 genus_name MALUS 4378
#> # ℹ 90 more rows
# Restricted to trees planted since 2020
get_cov_facets("public-trees", facet = "genus_name",
where = "date_planted >= date'2020-01-01'")
#> # A tibble: 74 × 3
#> facet value count
#> <chr> <chr> <int>
#> 1 genus_name ACER 2840
#> 2 genus_name QUERCUS 1298
#> 3 genus_name NYSSA 1027
#> 4 genus_name PRUNUS 924
#> 5 genus_name PARROTIA 859
#> 6 genus_name CARPINUS 855
#> 7 genus_name FAGUS 827
#> 8 genus_name MAGNOLIA 469
#> 9 genus_name FRAXINUS 372
#> 10 genus_name STYRAX 353
#> # ℹ 64 more rows
# }