# sunspot.year: Yearly Sunspot Data, 1700-1988

## Description

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.

## Usage

 `1` ```sunspot.year ```

## Format

The univariate time series `sunspot.year` contains 289 observations, and is of class `"ts"`.

## Source

H. Tong (1996) Non-Linear Time Series. Clarendon Press, Oxford, p. 471.

For monthly sunspot numbers, see `sunspot.month` and `sunspots`.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15``` ```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),end(sy)), 12)) # Dec 1983 s.m <- window(sm, start=t1, end=t2) s.y <- window(sy, start=t1, end=t2) # {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), tol = 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 ```