data frame containing at least a column giving the time (and date) (class POSIXct) of the measurements ordered by
sample and chronologically. A column containing the sample IDs is optionally required if several samples were measured.
sample
optional name of the column in data containing the sample ID, default: "sample"
date.and.time
optional name of the column in data containing the time (and date) as class POSIXct,
default: "date.and.time"
Value
the original data frame extended by a numerical vecor containing the time intervals
(min) between the measurements of a sample. The first values of each sample is NA since
time intervals are computed from row i and i-1.