R: Daily Wind Speeds in Dublin

DublinWind {cobs} | R Documentation

## Daily Wind Speeds in Dublin

### Description

The `DublinWind` data frame is basically the time series of daily average wind speeds from 1961 to 1978, measured in Dublin, Ireland. These are 6574 observations (18 full years among which four leap years).

### Usage

    data(DublinWind)

### Format

This data frame contains the following columns:

speed

  numeric vector of average daily wind speed in knots

day

  an integer vector giving the day number of the year, i.e., one of 1:366.

### Details

The periodic pattern along the 18 years measured and the autocorrelation are to be taken into account for analysis, see the references. This is Example 3 of the COBS paper.

### Source

From shar file available from http://www.cba.nau.edu/pin-ng/cobs.html

Also available from .......STATLIB..........

### References

Haslett, J. and Raftery, A. (1989) Space-Time Modelling with Long-Memory Dependence: Assessing Ireland's Wind Power Resource. .......... 38, 1–21.

COBS: Qualitatively Constrained Smoothing via Linear Programming; Computational Statistics 14, 315–337.

He, X. and Ng, P. (1999) COBS: Qualitatively Constrained Smoothing via Linear Programming; Computational Statistics 14, 315–337.

### Examples

    data(DublinWind)
    str(DublinWind)
    plot(speed ~ day, data = DublinWind)# not so nice; want time scale

    ## transform 'day' to correct "Date" object; and then plot
    Dday <- seq(from = as.Date("1961-01-01"), by = 1,
                length = nrow(DublinWind))
    plot(speed ~ Dday, data = DublinWind, type = "l",
         main = paste("DublinWind speed daily data, n=",
                      nrow(DublinWind)))

    ##--- ~ He & Ng "Example 3" %% much more is in ../tests/wind.R
    co.o50 <-
     with(DublinWind, ## use nknots > (default) 6 :
      cobs(day, speed, knots.add = TRUE, constraint= "periodic", nknots = 10,
           tau = .5, method = "uniform"))
    summary(co.o50)
    lines(Dday, fitted(co.o50), col=2, lwd = 2)

    ## the periodic "smooth" function - in one period
    plot(predict(co.o50), type = "o", cex = 0.2, col=2,
         xlab = "day", ylim = c(0,20))
    points(speed ~ day, data = DublinWind, pch = ".")

[Package cobs version 1.3-3 Index]