find.shells: Find nearby shell-derived dR values

In rice: Radiocarbon Equations

Find nearby shell-derived dR values

Description

Find the shells closest to a chosen coordinate, and plot the dR values and feeding ecology. Uses the marine database downloaded (30 Aug 2024) from calib.org/marine. See Reimer PJ, Reimer RW, 2001. A marine reservoir correction database and on-line interface. Radiocarbon 43:461-3.

Usage

find.shells(
  longitude,
  latitude,
  nearest = 50,
  browse = FALSE,
  colour = "dR",
  rainbow = FALSE,
  size = 2,
  mapsize = "large",
  mincol = "yellow",
  maxcol = "red",
  symbol = "feeding",
  symbol.legend = TRUE,
  legend.loc = c(0.95, 0.02),
  legend.size = c(0.05, 0.2),
  ocean.col = "aliceblue",
  land.col = rgb(0, 0.5, 0, 0.6),
  padding = 1,
  warn = TRUE,
  currents = TRUE
)

Arguments

longitude	Longitude of the point. Can only deal with one point at a time.
latitude	Latitude of the point. Can only deal with one point at a time.
nearest	The number of shell values to be returned. Defaults to 50.
browse	Type of map to provide. browse=FALSE (default) plots a static map in R's device (doesn't require Internet access), while browse=TRUE opens a browsable, interactive map in your Internet browser.
colour	The variable to be plotted as colour. Expects a continuous variable. Defaults to 'dR'.
rainbow	Whether or not to use a rainbow scale to plot the variable.
size	Size of the symbols. Defaults to 2.
mapsize	Resolution of the map. Can be "small" or "large". If the latter, a high-resolution dataset will have to be downloaded using the R package 'rnaturalearthhires'. Since this package is on github but not on CRAN, you will have to download it yourself (using the command devtools::install_github("ropensci/rnaturalearthhires")). Defaults to "small" if 'rnaturalearthhires' is not installed, and to "large" if it is installed.
mincol	Colour for minimum values.
maxcol	Colour for maximum values.
symbol	The variable to be plotted as symbol. Expects a categoric variable. Defaults to 'feeding'.
symbol.legend	Whether or not to plot the legend for the symbols.
legend.loc	Location of the legend, if using a basic plot. Defaults to the bottom right corner based on par("usr"), legend.loc=c(0.95, 0.02)
legend.size	Size of the legend, if using a basic plot. Defaults to legend.size=c(0.05, 0.2)
ocean.col	Colour for the oceans. Defaults to ocean.col="aliceblue".
land.col	Colour for the land. Defaults to semi-transparent darkgreen: land.col=rgb(0, 0.5, 0, 0.6).
padding	Area around the map if using a basic plot. Avoids strange line features. Defaults to padding=1.
warn	Whether or not to warn if some recommended R packages are not available.
currents	If set to TRUE (the default), the user will be asked if they want to browse a map of ocean currents. If the user responds 'y', an Internet browser window will be opened pointing to a zoomed-in map of ocean currents (at 50 m depth). The ocean currents are from 'earth.nullschool.net' and are based on an ocean circulation model which is updated daily. Owing to limitations of the website, the shell locations cannot currently be added to the page itself.

Details

This function uses the 'rnaturalearth' package for country maps. If the high-resolution maps are desired, the 'rnaturalearthhires' package must be installed from GitHub.

Value

A dataset with the n nearest dR values, and a plot of their coordinates.

Examples

  UK <- find.shells(0, 55, mapsize="small")
  mean(UK$dR)
  Caribbean <- find.shells(-70, 20, 30, mapsize="small")

rice documentation built on June 13, 2025, 5:09 p.m.