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SERG
Mapping with R
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!3
Cartograms example
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Merged
Cartograms example
twr1m15/mapping-with-r:cartograms-example
into
master
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1
Merged
Tom Rushby
requested to merge
twr1m15/mapping-with-r:cartograms-example
into
master
3 years ago
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Create LSOA and hexograms/cartograms examples.
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ec214c1c
Add example script using ONS open geog API and formatting/filtering query - plot with Leaflet.
· ec214c1c
Tom Rushby
authored
3 years ago
open-geog-API/ONS-open-geography-example.R
0 → 100644
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# 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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