source/posts/obtaining_SLIP_data_using_R.org

   1 #+date: <2023-10-11 23:41:54 +08:00>
   2 #+opengraph2: ogimage="https://www.vanrenterghem.biz/blog/pics/SLIP_WA_schools.png"
   3 #+filetags: R spatial analysis visualisation
   4 #+title: Obtaining WA Landgate Shared Location Information using R.
   5
   6 Six years ago, [[file:using spatial features and openstreetmap][I wrote about Simple Features (sf) in R]]. I mapped the number of pupils per high
   7 school in the Perth metro area. At the time, I didn't include how to
   8 obtain the shapefile, provided as open data by Landgate on behalf of the
   9 Western Australian government through its Shared Location Information
  10 Platform ([[https://data.wa.gov.au/slip][SLIP]]).
  11
  12 I have now updated the script,
  13 [[http://git.vanrenterghem.biz/?p=R/project-wa-schools.git;a=summary][available in my code repository]], with an R implementation of
  14 [[https://toolkit.data.wa.gov.au/hc/en-gb/articles/115000962734][the methodology in SLIP's How To Guides]] ([[https://web.archive.org/web/20230608184007/https://toolkit.data.wa.gov.au/hc/en-gb/articles/115000962734][Archive]]).
  15
  16 The relevant code looks as follows, simplified greatly through the use
  17 of the [[https://httr2.r-lib.org/][httr2]] library - the equivalent of the [[https://docs.python-requests.org/en/latest/][Requests]] library
  18 used in the Python example in the SLIP knowledge base:
  19
  20 #+BEGIN_SRC R
  21 library(httr2)
  22 tempdirSHP <- tempdir()
  23 tempfileSHP <- tempfile()
  24 # Create the token request
  25 req <- request("https://sso.slip.wa.gov.au/as/token.oauth2") |>
  26   req_headers("Authorization" = "Basic ZGlyZWN0LWRvd25sb2Fk") |>
  27   req_body_form(grant_type = "password", # SLIP username and password stored in
  28                                          # pass - the standard unix password manager
  29   username = system2("pass", args = "slip.wa.gov.au | grep Username | sed -e 's/Username: //'", stdout = TRUE),
  30   password = system2("pass", args = "slip.wa.gov.au | head -1", stdout = TRUE))
  31 # Obtain the token response
  32 tokenResponse <- req_perform(req)
  33 # Define the SLIP file to download
  34 slipUrl <- "https://direct-download.slip.wa.gov.au/datadownload/Education/Current_Active_Schools_Sem_1_2022_Public_DET_020_WA_GDA94_Public_Shapefile.zip"
  35 # Create the request for the SLIP file using the received token req <-
  36 request(slipUrl) |>
  37   req_headers( 'Authorization' = paste0('Bearer',resp_body_json(tokenResponse)$access_token))
  38 # Obtain the SLIP file using the created request
  39 responseSlip <- req_perform(req)
  40 #+END_SRC
  41
  42 An updated plot of the high school enrollment numbers looks as follows
  43 (for clarity, I've only included the names of schools in the top 5% as
  44 ranked by student numbers):
  45
  46 #+CAPTION: Pupil density in Western Australian high schools
  47 #+ATTR_HTML: :class img-fluid :alt Pupil density in Western Australian high schools
  48 [[file:../assets/SLIP_WA_schools.png]]