tsp(x) tsp(x) <- value start(x) end(x) frequency(x)
tsp returns the
tsp attribute of
x, which will be
NULL
if
x is not a time series.
The
tsp attribute has three values giving the starting time,
ending time, and the observation frequency of the time series.
start and
end return their times as a pair
of numbers: an integer number of time units, and the number
of observations times after that integer.
For example, for monthly series, with
frequency(x) equal
to 12, these are year and month.
frequency returns an integer giving the number of observations per unit time.
To explicitly delete the
tsp attribute,
use
tsp(x) <- NULL.
If
s is
start(x) and
t is
tsp(x), then
t[1] is the same as
s[1]+(s[2]-1)/t[3]
.
The output for
end is analogous.
The
tsp function is generic, though it currently has no methods defined
for it.
This makes the
start,
end and
frequency functions essentially
generic since they depend on
tsp.
Time series created by
ts have been superseded by the classed time
series created by
rts,
cts, and
its. You can coerce a old-style
time series to a new with
as.rts. View the time parameters of the
new time series with
tspar.
# find the tsp attribute of the ship dataset
tsp(ship) # 1967.000 1974.917 12.000
start(ship) # 1967
end(ship) # 1974 12
frequency(ship) # 12
# create a time series beginning at same time as ship
newdata <- rts(data, start = start(ship),
frequency = frequency(ship))