tangles (version 2.0.1)

detangles: Revert anonymised point patterns or raster objects

Description

Reverses the spatial anonymisation applied by the tangles function, restoring original XY coordinates or raster data. Requires a matching detangler object containing the transformation sequence and hash key. The restoration process preserves spatial relationships and supports both point and raster inputs.

Usage

detangles(
  data = NULL,
  tanglerInfo = NULL,
  raster_object = FALSE,
  stub = NULL,
  hash_key = NULL,
  saveTangles = FALSE,
  exportShapefile = FALSE,
  path = NULL
)

Value

A restored data.frame of spatial XY coordinates or a terra::SpatRaster object, depending on input type.

If saveTangles = TRUE, corresponding files are saved to path, including:

• detangledXY_<stub>_<hash>.rds

• detangledXY_raster_<name>.tif (for raster input)

• detangledXY_<stub>_<hash>.shp (for point shapefile export, if exportShapefile = TRUE)

Arguments

data

A 2-column matrix or data.frame of spatial coordinates, an sf POINT object, or a terra::SpatRaster object.

tanglerInfo

A detangler object returned by tangles(), containing the anonymisation steps and associated hash key.

raster_object

Logical; set to TRUE if the input is a raster object. This enables value restoration for all raster cells.

stub

Optional character string used in output file naming. Helps distinguish saved files.

hash_key

Character string representing the hash key to verify identity of the detangler. Must match tanglerInfo\$hash.

saveTangles

Logical; if TRUE, saves untangled data as .rds (and optionally raster .tif) files to path.

exportShapefile

Logical; if TRUE and input is point-based, a shapefile of the untangled coordinates is written (with undefined CRS).

path

Directory to save output files if saveTangles or exportShapefile is enabled. Defaults tempdir().

Author

Brendan Malone

References

• CM O’Keefe, S Otorepec, M Elliot, E Mackey, and K O’Hara (2017) The De-Identification Decision Making Framework. CSIRO Reports EP173122 and EP175702. tools:::Rd_expr_doi("10.4225/08/59c169433efd4")

Examples

# \donttest{
## EXAMPLE 1: Untangle point data.frame and export shapefile
library(sf)
set.seed(1)

# Simulate XY data
pts <- data.frame(X = runif(100), Y = runif(100))

# Anonymise
tangled <- tangles(data = pts, depth = 4, saveTangles = FALSE)

# Restore points
restored_pts <- detangles(
  data = tangled[[1]],
  tanglerInfo = tangled[[2]],
  raster_object = FALSE,
  stub = "points",
  hash_key = tangled[[2]]$hash,
  exportShapefile = TRUE
)

## EXAMPLE 2: Untangle from sf POINT input
sf_pts <- st_as_sf(pts, coords = c("X", "Y"))

# Anonymise sf object
tangled_sf <- tangles(data = sf_pts, depth = 3)

# Restore using sf input
restored_from_sf <- detangles(
  data = tangled_sf[[1]],
  tanglerInfo = tangled_sf[[2]],
  stub = "sf_restore",
  hash_key = tangled_sf[[2]]$hash,
  exportShapefile = TRUE
)

## EXAMPLE 3: Untangle raster data (terra)
library(terra)
ext_path <- system.file("extdata", package = "tangles")
rast.files <- list.files(path = ext_path, full.names = TRUE)
rasters <- terra::rast(rast.files)

# Anonymise raster
tangled_rast <- tangles(data = rasters, depth = 3, rasterdata = TRUE, raster_object = TRUE)

# Restore raster
restored_rast <- detangles(
  data = tangled_rast[[1]],
  tanglerInfo = tangled_rast[[2]],
  raster_object = TRUE,
  stub = "raster_demo",
  hash_key = tangled_rast[[2]]$hash,
  saveTangles = TRUE
)
# }