stratigraph (version 0.66)

a.datums: Returns first and last appearance datums

Description

Returns the first and last appearance datums (FADs and LADs) for taxa in a stratigraphic column.

Usage

a.datums(x, depths = NULL, skip = 0, increasing.down = FALSE, ...)
fads(x, depths = NULL, skip = 0, increasing.down = FALSE, ...)
lads(x, depths = NULL, skip = 0, increasing.down = FALSE, ...)

Arguments

x

an object of class strat.column.

depths

depths from which to calculate the datums

skip

a number of depths (levels) to skip, returning NA instead of values for FAD or LAD; defaults to 0.

increasing.down

FALSE (default) returns FADs less than or equal to LADs, as is the case when depths are measured up from the bottom of, e.g. a stratigraphic section; TRUE reverses FADs and LADs, as is the case when depths are measured from the surface in wells or cores.

...

not currently used.

Value

a.datums returns a data frame with columns fads and lads, each of which is a numeric vector giving the FAD or LAD of each taxon in the stratigraphic column. fads and lads return respectively just the fads and just the lads in a single named numeric vector.

Details

If depths is provided, it will clobber x$depths, should x$depths exist.

See Also

plot.strat.column, stratigraph

Examples

data(mohawk)
fads(as.strat.column(mohawk))
# should make mohawk a strat.column without coercion