Derive Custom Summary Statistics from Climate Variables
Source:R/derive_statistics.R
derive_statistics.RdCalculates a wide range of custom summary statistics for a primary climate variable, with options for interactions with a second variable. This function serves as a smart wrapper that automatically selects the most efficient processing workflow (in-memory vs. tiled).
Usage
derive_statistics(
variable,
stats = c("mean", "max", "min"),
inter_variable = NULL,
inter_stats = NULL,
prefix_variable = "var",
suffix_inter_max = "inter_high",
suffix_inter_min = "inter_low",
output_dir = tempdir(),
period_length = 3,
period_stats = "mean",
circular = TRUE,
user_region = NULL,
method = c("auto", "tiled", "terra"),
tile_degrees = 5,
gdal_opt = c("COMPRESS=DEFLATE", "PREDICTOR=3", "NUM_THREADS=ALL_CPUS"),
overwrite = FALSE,
...
)Arguments
- variable
A `terra::SpatRaster` object for the primary variable.
- stats
A character vector of statistics to compute for the primary variable. Supported: `"mean"`, `"max"`, `"min"`, `"sum"`, `"stdev"`, `"cv_cli"`, `"max_period"`, `"min_period"`.
- inter_variable
(Optional) A `terra::SpatRaster` for an interactive variable.
- inter_stats
(Optional) A character vector of interactive statistics to compute. Requires `inter_variable`. Supported: `"max_inter"`, `"min_inter"`.
- prefix_variable
A character string used as the prefix for all output file names (e.g., `prefix_variable = "wind"` results in "wind_mean.tif", "wind_max.tif").
- suffix_inter_max
Character. Suffix for the "max_inter" statistic name. Default: "inter_high".
- suffix_inter_min
Character. Suffix for the "min_inter" statistic name. Default: "inter_low".
- output_dir
The directory where the final summary rasters will be saved.
- period_length
Integer. The number of temporal units defining a "period". Default: 3.
- period_stats
Character. The statistic ("mean" or "sum") to summarize data over each period. Default: "mean".
- circular
Logical. If `TRUE` (the default), period calculations wrap around.
- user_region
(Optional) An `sf` or `terra::SpatVector` object defining the area of interest.
- method
The processing method. See Details for more information.
- tile_degrees
(Tiled method only) The approximate size of processing tiles.
- gdal_opt
(Optional) A character vector of GDAL creation options for the output GeoTIFF files.
- overwrite
(Optional) Logical. If `FALSE` (the default), the function will stop if output files already exist.
- ...
Additional arguments, primarily for passing static index `SpatRaster` objects. See the "Static Indices" section.
Details
This function provides a flexible alternative to `derive_bioclim()` for any multi-layer climate variable (e.g., wind speed, humidity). It unifies two processing backends, controlled by the `method` argument:
`"auto"`: (Default) Intelligently chooses between "terra" and "tiled".
`"terra"`: Forces the fast, in-memory workflow.
`"tiled"`: Forces the memory-safe, out-of-core workflow. Requires that all input SpatRasters point to files on disk.