CacheGeo {reproducible}

Cache-like function for spatial domains

Description

Usage

CacheGeo(
  targetFile = NULL,
  url = NULL,
  domain,
  FUN,
  destinationPath = getOption("reproducible.destinationPath", "."),
  useCloud = getOption("reproducible.useCloud", FALSE),
  cloudFolderID = NULL,
  purge = FALSE,
  useCache = getOption("reproducible.useCache"),
  overwrite = getOption("reproducible.overwrite"),
  action = c("nothing", "update", "replace", "append"),
  ...
)

Arguments

targetFile

The (optional) local file (or path to file)

url

The (optional) url of the object on Google Drive (the only option currently). This is only for downloading and uploading to.

domain

An sf polygon object that is the spatial area of interest. If NULL, then this will return the whole object in targetFile.

FUN

A function call that will be called if there is the domain is not already contained within the sf object at url or targetFile. This function call MUST return either a sf class object or a data.frame class object that has a geometry column (which can then be converted to sf with st_as_sf)

destinationPath

Character string of a directory in which to download and save the file that comes from url and is also where the function will look for archive or targetFile. NOTE (still experimental): To prevent repeated downloads in different locations, the user can also set options("reproducible.inputPaths") to one or more local file paths to search for the file before attempting to download. Default for that option is NULL meaning do not search locally.

useCloud

A logical.

cloudFolderID

If this is specified, then it must be either 1) a googledrive url to a folder where the targetFile will be read from or written to, or 2) a googledrive id or 3) an absolute path to a (possibly non-existent yet) folder on your google drive.

purge

Logical or Integer. 0/FALSE (default) keeps existing CHECKSUMS.txt file and prepInputs will write or append to it. 1/TRUE will deleted the entire CHECKSUMS.txt file. Other options, see details.

useCache

Passed to Cache in various places. Defaults to getOption("reproducible.useCache", 2L) in prepInputs, and getOption("reproducible.useCache", FALSE) if calling any of the inner functions manually. For prepInputs, this mean it will use Cache only up to 2 nested levels, which includes preProcess. postProcess and its nested ⁠*Input⁠ functions (e.g., cropInputs, projectInputs, maskInputs) are no longer internally cached, as terra processing speeds mean internal caching is more time consuming. We recommend caching the full prepInputs call instead (e.g. prepInputs(...) |> Cache()).

overwrite

Logical. Should downloading and all the other actions occur even if they pass the checksums or the files are all there.

action

A character string, with one of c("nothing", "update", "replace", "append"). Partial matching is used ("n" is sufficient). nothing will prevent any updating of the targetFile, i.e., "read only". append will add the spatial elements in domain to targetFile (and writing it back to disk). update will do the same as append, but will also remove any identical geometries before appending. replace does nothing currently.

...

Any named objects that are needed for FUN

Details

This function is a combination of Cache and prepInputs but for spatial domains. This differs from Cache in that the current function call doesn't have to have an identical function call previously run. Instead, it needs to have had a previous function call where the domain being passes is within the geographic limits of the targetFile or file located at the url. This is similar to a geospatial operation on a remote GIS server, with 2 differences:

1. This downloads the object first before doing the GIS locally, and 2. it will optionally upload an updated object if the geographic area did not yet exist.

This has a very specific use case: assess whether an existing sf polygon or multipolygon object (local or remote) covers the spatial area of a domain of interest. If it does, then return only that part of the sf object that completely covers the domain. If it does not, then run FUN. It is expected that FUN will produce an sf polygon or multipolygon class object. The result of FUN will then be appended to the sf object as a new entry (feature) or it will replace the existing "same extent" entry in the sf object.

Value

Returns an object that results from FUN, which will possibly be a subset of a larger spatial object that is specified with targetFile or url.

Examples

if (requireNamespace("sf", quietly = TRUE) &&
    requireNamespace("terra", quietly = TRUE)) {
dPath <- checkPath(file.path(tempdir2()), create = TRUE)
localFileLux <- system.file("ex/lux.shp", package = "terra")

  # 1 step for each layer
  # 1st step -- get study area
  full <- prepInputs(localFileLux, destinationPath = dPath) # default is sf::st_read
  zoneA <- full[3:6, ]
  zoneB <- full[8, ] # not in A
  zoneC <- full[3, ] # yes in A
  zoneD <- full[7:8, ] # not in A, B or C
  zoneE <- full[3:5, ] # yes in A
  # 2nd step: re-write to disk as read/write is lossy; want all "from disk" for this ex.
  writeTo(zoneA, writeTo = "zoneA.shp", destinationPath = dPath)
  writeTo(zoneB, writeTo = "zoneB.shp", destinationPath = dPath)
  writeTo(zoneC, writeTo = "zoneC.shp", destinationPath = dPath)
  writeTo(zoneD, writeTo = "zoneD.shp", destinationPath = dPath)
  writeTo(zoneE, writeTo = "zoneE.shp", destinationPath = dPath)
  # Must re-read to get identical columns
  zoneA <- sf::st_read(file.path(dPath, "zoneA.shp"))
  zoneB <- sf::st_read(file.path(dPath, "zoneB.shp"))
  zoneC <- sf::st_read(file.path(dPath, "zoneC.shp"))
  zoneD <- sf::st_read(file.path(dPath, "zoneD.shp"))
  zoneE <- sf::st_read(file.path(dPath, "zoneE.shp"))

  # The function that is to be run. This example returns a data.frame because
  #    saving `sf` class objects with list-like columns does not work with
  #    many st_driver()
  fun <- function(domain, newField) {
    domain |>
      as.data.frame() |>
      cbind(params = I(lapply(seq_len(NROW(domain)), function(x) newField)))
  }

  # Run sequence -- A, B will add new entries in targetFile, C will not,
  #                 D will, E will not
  for (z in list(zoneA, zoneB, zoneC, zoneD, zoneE)) {
    out <- CacheGeo(
      targetFile = "fireSenseParams.rds",
      domain = z,
      FUN = fun(domain, newField = I(list(list(a = 1, b = 1:2, c = "D")))),
      fun = fun, # pass whatever is needed into the function
      destinationPath = dPath,
      action = "update"
      # , cloudFolderID = "cachedObjects" # to upload/download from cloud
    )
  }
}