the method constructs an object from a dataframe a timelag format using the given interpolating function
Arguments
map
A data frame containing exactly two columns:
the first one is interpreted as time
the second one is interpreted as atmospheric C14 fraction in the format mentioned
lag
a scalar describing the time lag. Positive Values shift the argument of the interpolation function forward in time. (retard its effect)
format
a string that specifies the format used to represent the atmospheric fraction. Possible values are "Delta14C" which is the default or "afn" the Absolute Fraction Normal representation
interpolation
A function that returns a function the default is splinefun. Other possible values are the linear interpolation approxfun or any self made function with the same interface.