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.
find.shells(
longitude,
latitude,
nearest = 50,
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
)A dataset with the n nearest dR values, and a plot of their coordinates.
Longitude of the point. Can only deal with one point at a time.
Latitude of the point. Can only deal with one point at a time.
The number of shell values to be returned. Defaults to 50.
The variable to be plotted as colour. Expects a continuous variable. Defaults to 'dR'.
Whether or not to use a rainbow scale to plot the variable.
Size of the symbols. Defaults to 2.
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.
Colour for minimum values.
Colour for maximum values.
The variable to be plotted as symbol. Expects a categoric variable. Defaults to 'feeding'.
Whether or not to plot the legend for the symbols.
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)
Size of the legend, if using a basic plot. Defaults to legend.size=c(0.05, 0.2)
Colour for the oceans. Defaults to ocean.col="aliceblue".
Colour for the land. Defaults to semi-transparent darkgreen: land.col=rgb(0, 0.5, 0, 0.6).
Area around the map if using a basic plot. Avoids strange line features. Defaults to padding=1.
Whether or not to warn if some recommended are not available.
This function uses the `rnaturalearth` package for country maps. If the high-resolution maps are desired, the `rnaturalearthhires` package must be installed from GitHub.
UK <- find.shells(0, 55, mapsize="small")
mean(UK$dR)
Caribbean <- find.shells(-70, 20, 30, mapsize="small")
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