Hands-On Exploratory Data Analysis with R

Spectrum plots

Spectrum plots generate spectral densities of the time series. We will implement the following steps to create spectrum plots for the dataset indicated. Spectrum plots create a separate variation with time series representations. The following syntax is used to create a spectrum plot:

spectrum(x, ..., method = c("pgram", "ar"))

Here, the parameters refer to the following:

• x: A univariate or multivariate time series.
• method: A string specifying the method used to estimate the spectral density. Permitted methods are pgram (the default) and ar, which can be abbreviated.

Now, let's create a spectral plot for our dataset. The spectral plots take all attributes together:

> require(graphics) > spectrum(AirQualityUCI, method = c("pgram", ...