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have been superseded by the classed time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))