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 attractive 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.

Usage

networkMap(
  source = "aurn",
  control = NULL,
  year = NULL,
  cluster = TRUE,
  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.
"kcl", 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").

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:

"variable" to toggle between different pollutants
"site_type" for different site classifications
"agglomeration", "zone" or "local_authority" for different regions of the UK
"network" for different monitoring networks, if more than one source is provided.

year

A year, or range of years, with which to filter data.

default: NULL

By default, networkMap() visualises sites which are currently operational. year allows users to show sites open in a specific year, or over a range of years. See openair::importMeta() for more information.

cluster

Cluster markers together when zoomed out?

default: TRUE

When cluster = TRUE, markers are clustered together. This may be useful for sources like "kcl" where there are many markers very close together. Defaults to TRUE, and is forced to be TRUE when source = "europe" due to the large number of sites.

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.

Details

When selecting multiple data sources using source, please be mindful that there can be overlap between the different networks. For example, an air quality site in Scotland may be part of the AURN and the SAQN. networkMap() will only show one marker for such sites, and uses the order in which source arguments are provided as the hierarchy by which to assign sites to networks. The aforementioned AURN & SAQN site will therefore have its SAQN code displayed if source = c("saqn", "aurn"), and its AURN code displayed if source = c("aurn", "saqn").

This hierarchy is also reflected when control = "network" is used. As leaflet markers cannot be part of multiple groups, the AURN & SAQN site will be part of the "SAQN" layer control group when source = c("saqn", "aurn") and the "AURN" layer control group when source = c("aurn", "saqn").

Examples