metadata,
data and processingLog.pt[["time"]], where the
string could also be "latitude", etc. Assignment to these can be
made with e.g. pt[["latitude"]] <- value, etc. Indeed, any quantity
in the metadata slot or the data slot can be retrieved or
updated in this way.drifter object may be read with read.drifter or created
with as.drifter. Plots can be made with
plot.drifter, while summary.drifter produces
statistical summaries and show produces overviews.