Create a leaflet map of air quality measurement network sites

This function uses openair::importMeta() to obtain metadata for measurement sites and uses it to create an interactive leaflet map. By default a map will be created in which readers may toggle between a vector base map and a satellite/aerial image, although users can further customise the control menu using the provider and control parameters. Any argument which can be passed to openair::importMeta() can be passed via ..., with the exception of all and duplicate.

Usage

networkMap(
  source = "aurn",
  ...,
  control = NULL,
  cluster = NULL,
  provider = c(Default = "OpenStreetMap", Satellite = "Esri.WorldImagery"),
  legend = TRUE,
  legend.position = "topright",
  control.collapsed = FALSE,
  control.position = "topright"
)

Arguments

source

One or more UK or European monitoring networks.

default: "aurn"

One or more air quality networks for which data is available through openair. Available networks include:

"aurn", The UK Automatic Urban and Rural Network.
"aqe", The Air Quality England Network.
"saqn", The Scottish Air Quality Network.
"waqn", The Welsh Air Quality Network.
"ni", The Northern Ireland Air Quality Network.
"local", Locally managed air quality networks in England.
"imperial", Imperial College London (formerly King's College London) networks.
"europe", European AirBase/e-reporting data.

There are two additional options provided for convenience:

"ukaq" will return metadata for all networks for which data is imported by importUKAQ() (i.e., AURN, AQE, SAQN, WAQN, NI, and the local networks).
"all" will import all available metadata (i.e., "ukaq" plus "kcl" and "europe").

...

Arguments passed on to openair::importMeta

year: If a single year is selected, only sites that were open at some point in that year are returned. If all = TRUE only sites that measured a particular pollutant in that year are returned. Year can also be a sequence e.g. year = 2010:2020 or of length 2 e.g. year = c(2010, 2020), which will return only sites that were open over the duration.
pollutant: Character vectors used to search the metadata for the specified sources. pollutant is case-insensitive. For example, pollutant = c("nox", "o3") will return sites which measure either NOx or O3. Can also take the shorthand "hc", will returns all hydrocarbons. Similar to code, values are matched exactly (e.g., pollutant = "no" will only return NO and not NO2 or NOx). Note that pollutant only applies to networks available through importUKAQ().
site,code,site_type: Character vectors used to search the metadata for the specified sources. All of code, site and site_type are case-insensitive. code and site_type are matched exactly, but site is 'pattern matched' - e.g., site = "Sunderland" and source = "aurn" will return data for "Sunderland", "Sunderland Silksworth" and "Sunderland Wessington Way" (plus any future sites with the string "Sunderland" in their name).
lat,lng: Decimal latitude (lat) and longitude (lng) (or other Y/X coordinate if using a different crs). If provided, the data will be returned with a distance_km column displaying the distance of each station from the target coordinate. The data will also be automatically sorted by this column.
crs: The coordinate reference system (CRS) of the data, passed to sf::st_crs(). By default this is EPSG:4326, the CRS associated with the commonly used latitude and longitude coordinates. Different coordinate systems can be specified using crs (e.g., crs = 27700 for the British National Grid). Note that non-lat/lng coordinate systems will be re-projected to EPSG:4326 for comparison with the site metadata.
max_dist,max_n: If lat and lng are provided, max_dist and max_n further filter the metadata. max_dist defines a maximum distance from the target coordinate in kilometers, and max_n a maximum number of sites to be returned. max_n is applied after max_dist.

control

Option to create a 'layer control' menu.

default: NULL

A string to specify categories in a "layer control" menu, to allow readers to select between different site categories. Choices include:

"source" to toggle between different networks
"variable" to toggle between different pollutants
"site_type" for different site classifications
"agglomeration", "zone" or "local_authority" for different regions of the UK

cluster

Cluster markers together when zoomed out?

default: NULL

When cluster = TRUE, markers are clustered together. This may be useful for sources like "imperial" where there are many markers very close together. Defaults to NULL, which is TRUE if there are more than 25 sites mapped and FALSE if there are fewer.

provider

The basemap(s) to be used.

default: c("Default" = "OpenStreetMap", "Satellite" = "Esri.WorldImagery")

Any number of leaflet::providers. See http://leaflet-extras.github.io/leaflet-providers/preview/ for a list of all base maps that can be used. If multiple base maps are provided, they can be toggled between using a "layer control" interface. By default, the interface will use the provider names as labels, but users can define their own using a named vector (e.g., c("Default" = "OpenStreetMap", "Satellite" = "Esri.WorldImagery"))

legend

Draw a shared legend?

default: TRUE

When multiple sources are defined, should a shared legend be created at the side of the map?

legend.position

Position of the legend

default: "topright"

Where should the shared legend be placed? One of "topleft", "topright", "bottomleft" or "bottomright". Passed to the position argument of leaflet::addLayersControl().

control.collapsed

Show the layer control as a collapsed?

default: FALSE

Should the "layer control" interface be collapsed? If TRUE, users will have to hover over an icon to view the options.

control.position

Position of the layer control menu

default: "topright"

Where should the "layer control" interface be placed? One of "topleft", "topright", "bottomleft" or "bottomright". Passed to the position argument of leaflet::addLayersControl().

Value

A leaflet object.

Examples

if (FALSE) { # \dontrun{
# view one network, grouped by site type
networkMap(source = "aurn", control = "site_type")

# view multiple networks, grouped by network
networkMap(source = c("aurn", "waqn", "saqn"), control = "network")
} # }