The Big R-Book

♣10♣Time Series Analysis

10.1 Time Series in R

Time series are lists of data points in which each data point is associated with a time-stamp. A simple example is the price of a stock in the stock market at different points of time on a given day. Another example is the amount of rainfall in a region at different months of the year. R language uses many functions to create, manipulate and plot the time series data. The data for the time series is stored in an R object called time series object. It is also a R data object like a vector or data frame.

time series

time-stamp

10.1.1 The Basics of Time Series in R

10.1.1.1 The Function ts()

The time series object is created by using the ts() function.

Function use for ts()

ts(data = NA, start = 1, end = numeric(), frequency = 1,

     deltat = 1, ts.eps = getOption(“ts.eps”), class = ,

     names = )

with

• data: A vector or matrix containing the values used in the time series.
• start: The start time for the first observation in time series.
• end: The end time for the last observation in time series.
• frequency The number of observations per unit time.
  • – frequency = 12: pegs the data points for every month of a year.
  • – frequency = 4: pegs the data points for every quarter of a year.
  • – frequency = 6: pegs the data points for every 10 minutes of an hour.
  • – frequency = 24 × 6: pegs the data points for every 10 minutes of a day.

Except the parameter “data” all other parameters are optional. To check if an object is a ...