sunspot.year {datasets} | R Documentation

## 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

    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.

### See Also

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

### Examples

    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), 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

[Package datasets version 3.3.2 Index]