A function that reads time-slice rasters of data for a given climate (typically processed data from a climate model run, such as the results of an analysis using PaleoView (Fordham, *et al.* 2017, Ecography)) in a given directory and calculates average deviation per year across time slices.
deviationThroughTime(variableDirectory, timeSlicePeriod, fileExtension = "asc")A directory containing at least two time slice rasters for a given climate variable.
Either a single number, in years, representing the time period elapsed between temporally-even climate variable raster slices, or a vector corresponding to periods, in years, between temporally-uneven time slices.
a character that describes a fileExtension corresponding to one of the suported drivers in
gdal
A raster showing the geographic distribution of climate deviation through time for a particular climate variable.
Make sure that files in the `variableDirectory` are read into `R` in order.
If you are specifying temporally-uneven time slices with `timeSlicePeriod`, make sure that each number corresponds to the number of years elapsed *between* time slices, *in the same order as the files were read into `R`*. There should be one less number than the number of files, and you must have at least three files in the directory.
See `precipDeviation.asc` and `temperatureDeviation.asc` for examples of rasters created using this function. See reference for data source details.
Owens, H.L., Guralnick, R., 2019. climateStability: An R package to estimate climate stability from time-slice climatologies. Biodiversity Informatics 14, 8–13. https://doi.org/10.17161/bi.v14i0.9786
# Generate sample data
td <- tempdir()
suppressWarnings(x <- terra::rast(nrows=20, ncols=20,
xmin=0, xmax=10, ymin=0, ymax=10,
vals = c(10,10,10,10,20)))
x2 <- x * 1.01
rastStack <- c(x, x2, x)
terra::writeRaster(rastStack, filename = paste0(td, "/raster",
1:terra::nlyr(rastStack), ".tif"),
overwrite = TRUE)
# Even time slices
testResult <- deviationThroughTime(td, timeSlicePeriod = 100,
fileExtension = "tif")
#> [1] "/var/folders/bn/2vhstsbj041cx84rt_n8rv080000gp/T//RtmpVXrmAo/raster1.tif"
#> [2] "/var/folders/bn/2vhstsbj041cx84rt_n8rv080000gp/T//RtmpVXrmAo/raster2.tif"
#> [3] "/var/folders/bn/2vhstsbj041cx84rt_n8rv080000gp/T//RtmpVXrmAo/raster3.tif"
# Uneven time slices
testResult <- deviationThroughTime(variableDirectory = td,
timeSlicePeriod = c(25, 100),
fileExtension = "tif")
#> [1] "/var/folders/bn/2vhstsbj041cx84rt_n8rv080000gp/T//RtmpVXrmAo/raster1.tif"
#> [2] "/var/folders/bn/2vhstsbj041cx84rt_n8rv080000gp/T//RtmpVXrmAo/raster2.tif"
#> [3] "/var/folders/bn/2vhstsbj041cx84rt_n8rv080000gp/T//RtmpVXrmAo/raster3.tif"
# Delete temporary files
unlink(td)