rice (version 2.2.0)

smooth.curve: Smooth a calibration curve

Description

Smooth a calibration curve over a time window of a specified width. This to accommodate material that has accumulated over a certain assumed time, e.g. a cm of peat over say 30 years.

Usage

smooth.ccurve(
  smooth = 30,
  cc = 1,
  postbomb = FALSE,
  glue = 0,
  cc.dir = c(),
  thiscurve = c(),
  resample = 0,
  name = "smoothed.csv",
  save = FALSE,
  sep = "\t"
)

Arguments

smooth

The window width of the smoothing. Defaults to smooth=30.

cc

The calibration curve to smooth. Calibration curve for 14C dates: 'cc=1' for IntCal20 (northern hemisphere terrestrial), 'cc=2' for Marine20 (marine), 'cc=3' for SHCal20 (southern hemisphere terrestrial). Alternatively, one can also write, e.g., "IntCal20", "Marine13". One can also make a custom-built calibration curve, e.g. using 'mix.ccurves()', and load this using 'cc=4'. In this case, it is recommended to place the custom calibration curve in its own directory, using 'cc.dir' (see below).

postbomb

Use 'postbomb=TRUE' to get a postbomb calibration curve (default 'postbomb=FALSE'). For monthly data, type e.g. 'ccurve("sh1-2_monthly")'

glue

Glue postbomb and prebomb curves together. Defaults to 0 (none), can be 1 (IntCal20 + NH1), 2 (IntCal20 + NH2), 3 (IntCal20 + NH3), 4 (SHCal20 + SH1-2) or 5 (SHCal20 + SH3). Note that this will override the value of cc.

cc.dir

Directory of the calibration curves. Defaults to where the package's files are stored (system.file), but can be set to, e.g., 'cc.dir="ccurves"'.

thiscurve

As an alternative to providing cc and/or postbomb, the data of a specific curve can be provided (3 columns: cal BP, C14 age, error). Defaults to c().

resample

The IntCal curves come at a range of 'bin sizes'; every year from 0 to 5 kcal BP, then every 5 yr until 15 kcal BP, then every 10 yr until 25 kcal BP, and every 20 year thereafter. The curves can be resampled to constant bin sizes, e.g. 'resample=5'. Defaults to FALSE.

name

The filename of the curve, if it is being saved. Defaults to name="smoothed.csv".

save

Whether or not to save the curve to cc.dir. Defaults to save=FALSE.

sep

Separator between fields if the file is saved (tab by default, sep="\t").

Author

Maarten Blaauw

Details

The smoothing is done by calculating the mean C14 age and error of a moving window (moving along with the cal BP steps of the calibration curve). Something similar is done in the online calibration software CALIB.

Examples

 mycurve <- smooth.ccurve(smooth=50)
 calibrate(2450,20, thiscurve=mycurve)