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Process multiple raster files from a directory

Source: R/process_rasters.R
process_raster_collection.Rd

This function processes multiple raster files in a directory by applying process_raster_with_boundaries() to each file and combining the results. Includes progress tracking and error handling.

Usage

process_raster_collection(
  directory,
  shapefile,
  id_cols = c("adm0", "adm1", "adm2"),
  pattern = "\\.tif$",
  aggregations = c("mean"),
  layer_to_process = 1,
  raster_is_density = FALSE,
  year_extractor = NULL
)

Arguments

directory

Directory containing raster files to process

shapefile

sf/SpatVector object with administrative boundaries. Must be in the same coordinate reference system (CRS) as the raster data

id_cols

Vector of column names from shapefile to include in output. Default is c("adm0", "adm1", "adm2") for country and first admin level

pattern

Regular expression pattern to match raster files. Default is "\.tif$" to match all .tif files

aggregations

Vector of aggregation methods to calculate. Supported values are "mean", "sum", and "median". Default is c("mean")

layer_to_process

Integer or character. Specifies which layer in a multi-layer raster to extract. If the raster contains multiple layers (e.g., different years or indicators), this argument selects the layer to be processed. Default is 1.

raster_is_density

Logical indicating if raster values represent density. If TRUE, values are converted from density to counts using cell area. Default is FALSE.

year_extractor

Optional function. A custom function that accepts a filename (character) and returns a year as integer or character. Passed through to extract_time_components(). Use this when the default "last plausible 4-digit year in 1980-2099" heuristic picks the wrong year (for example with malariaAtlas filenames that contain multiple year-like tokens). Defaults to NULL, which uses the built-in extractor.

Value

A combined data frame containing results from all processed files, sorted by time unit if available. Has the same structure as output from process_raster_with_boundaries() but with multiple files combined.

Details

The function:

  1. Lists all files in directory matching the pattern

  2. Creates a progress bar for tracking

  3. Processes each file using process_raster_with_boundaries()

  4. Combines results into a single data frame

  5. Sorts by time unit if available

Examples

if (FALSE) { # \dontrun{
# Process all CHIRPS files in a directory
districts <- sf::st_read("districts.shp")
results <- process_raster_collection(
  directory = "chirps_data",
  shapefile = districts,
  id_cols = c("COUNTRY", "DISTRICT"),
  pattern = "chirps.*\\.tif$",
  aggregations = c("mean", "sum")
)
} # }