| sunspot.year | R Documentation |
Yearly numbers of sunspots from 1700 to 1988 (rounded to one digit).
Note that monthly numbers are available as
sunspot.month, though starting slightly later.
sunspot.year
The univariate time series sunspot.year contains 289
observations, and is of class "ts".
H. Tong (1996) Non-Linear Time Series. Clarendon Press, Oxford, p. 471.
For monthly sunspot numbers, see sunspot.month
and sunspots.
Regularly updated yearly sunspot numbers are available from WDC-SILSO, Royal Observatory of Belgium, at http://www.sidc.be/silso/datafiles
utils::str(sm <- sunspots)# the monthly version we keep unchanged
utils::str(sy <- sunspot.year)
## The common time interval
(t1 <- c(max(start(sm), start(sy)), 1)) # Jan 1749
(t2 <- c(min( end(sm)[1],end(sy)[1]), 12)) # Dec 1983
s.m <- window(sm, start=t1, end=t2)
s.y <- window(sy, start=t1, end=t2[1]) # {irrelevant warning}
stopifnot(length(s.y) * 12 == length(s.m),
## The yearly series *is* close to the averages of the monthly one:
all.equal(s.y, aggregate(s.m, FUN = mean), tolerance = 0.0020))
## NOTE: Strangely, correctly weighting the number of days per month
## (using 28.25 for February) is *not* closer than the simple mean:
ndays <- c(31, 28.25, rep(c(31,30, 31,30, 31), 2))
all.equal(s.y, aggregate(s.m, FUN = mean)) # 0.0013
all.equal(s.y, aggregate(s.m, FUN = weighted.mean, w = ndays)) # 0.0017
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