Commit 05b986e5 authored by Tom Rushby's avatar Tom Rushby
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Merge branch 'master' into 'master'

Add ONS Open Geog API example

See merge request SERG/mapping-with-r!2
parents c7f6221b a6ca97ca
......@@ -4,6 +4,22 @@ Simple (and not so simple) examples of mapping data with R
You might also like https://git.soton.ac.uk/twr1m15/la_emissions_viz which drives https://rushby.shinyapps.io/LAemissions/
## data
The following example data is provided in this repository:
* Boundary data - for Solent region (various geographies: LA, LSOA, MSOA)
* Energy - area-based statistics for domestic electricity consumption (LSOA, MSOA)
* Lookup table for geographies
## rMappingExample
A simple example of mapping using R. Examples use Local Authority (LA) and Middle-layer Super Output Area (MSOA) geography and electricity consumption data (provided in `data` subfolder).
## ONS-open-geography
An example and resources for using the [ONS Open Geography portal](https://geoportal.statistics.gov.uk) to download geographical data and create maps using `Leaflet` package.
## Resources
### Openstreetmap for base maps (i.e. map tiles/rasters)
......@@ -18,4 +34,4 @@ They want you to have an API key now. Yeah nah.
### tmap package - nice - check out the bubble geom
* https://cran.r-project.org/web/packages/tmap/vignettes/tmap-getstarted.html
\ No newline at end of file
* https://cran.r-project.org/web/packages/tmap/vignettes/tmap-getstarted.html
# get feature layer data from ONS open geography API
# Really useful example of using ONS open geography portal with R
# https://medium.com/@traffordDataLab/pushing-the-boundaries-with-the-open-geography-portal-api-4d70637bddc3
library(sf)
# Load Local Authority geography from ----
# https://geoportal.statistics.gov.uk/datasets/ons::local-authority-districts-december-2020-uk-bgc/api
# Construct query URL from elements
geo_endpoint <- "https://ons-inspire.esriuk.com/arcgis/rest/services/"
geo_boundarylayer <- "Administrative_Boundaries/Local_Authority_Districts_December_2020_UK_BGC/"
geo_server <- "FeatureServer/0/"
geo_search <- "LAD20NM IN "
# Construct a vector of local authorities to load
# the following local authorities are the 'Solent' region
las_to_load <- c("Southampton","Portsmouth","Winchester",
"Eastleigh","Isle of Wight","Fareham",
"Gosport","Test Valley","East Hampshire",
"Havant","New Forest","Hart","Basingstoke and Deane")
geo_where <- las_to_load # sometimes we don't want all boundaries
geo_outfields <- "*" # returns all fields
#geo_outfields <- c("LAD20CD","LAD20NM","LONG","LAT") # use in place of line above to return selected fields only
geo_outSR <- "4326"
geo_format <- "json"
# Assemble the full URL for the query from elements above
geo_query_string <- paste0(geo_endpoint,geo_boundarylayer,geo_server,
"query?where=",geo_search,"(",paste(paste0("'",geo_where,"'"), collapse = ","),
")&outFields=",(paste(geo_outfields, collapse = ",")),"&outSR=",geo_outSR,"&f=",geo_format)
# Format the URL to remove spaces
geo_query <- URLencode(geo_query_string)
message("Loading LA geometry from ONS Open Geography API")
# API query
sf_data <- st_read(geo_query)
#plot(st_geometry(sf_data))
# Useful lookup spatial reference for CRS
# https://spatialreference.org/ref/epsg/27700/
st_coord_sys <- st_crs(sf_data) # check coord system
st_coord_sys # current coord system EPSG: 4326 (is what leaflet wants - good)
# transform the coord system if required
if(st_coord_sys$epsg != 4326){
sf_data <- st_transform(sf_data, "+proj=longlat +datum=WGS84")
}
# Create map (using leaflet) ----
# create popup first (using htmltools)
# by adding a column to sf_data object
library(htmltools)
sf_data$popup_text <-
paste("Locial authority area code: ","<b>", sf_data$lad20cd, "</b>",
'<br/>', 'Local authority: ', '<b>', sf_data$lad20nm, '</b>', ' ') %>%
lapply(htmltools::HTML)
# plot map
library(leaflet)
leaflet(sf_data) %>%
addTiles() %>% # Add default OpenStreetMap map tiles
addPolygons(color = "blue", fillColor = "blue", fillOpacity = 0.2, weight = 1.5, popup = ~(lad20nm), # popups clicked
label = ~(popup_text), # define labels
labelOptions = labelOptions( # label options
style = list("font-weight" = "normal", padding = "2px 2px"),
direction = "auto"),
highlight = highlightOptions(
weight = 5,
color = "#666",
fillOpacity = 0.7,
bringToFront = TRUE))
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