Takes a multi-band raster with one band per month and aggregates to annual and seasonal periods. Season definitions are configurable.
Usage
cd_aggregate(x, method = "mean", seasons = cd_seasons())Arguments
- x
A terra::SpatRaster with 12 bands (one per month, Jan through Dec).
- method
Character. Aggregation method:
"mean"or"sum". Default"mean". Use"sum"for precipitation.- seasons
Named list of integer vectors defining month groups. Default uses standard meteorological seasons: winter (DJF), spring (MAM), summer (JJA), fall (SON).
Value
A named list of terra::SpatRaster objects, one per period.
Names are "annual", plus the names from seasons.
Examples
if (FALSE) { # \dontrun{
# 12-band raster (one per month)
r <- terra::rast(nrows = 10, ncols = 10, nlyrs = 12)
terra::values(r) <- matrix(rnorm(1200), 100, 12)
# Default seasons
periods <- cd_aggregate(r)
names(periods) # "annual", "winter", "spring", "summer", "fall"
# Custom seasons (e.g., wet/dry)
cd_aggregate(r, seasons = list(wet = 10:3, dry = 4:9))
} # }