Exercise

# Identifying the sampling frequency

In addition to viewing your data and plotting over time, there are several additional operations that can be performed on time series datasets.

The `start()`

and `end()`

functions return the time index of the first and last observations, respectively. The `time()`

function calculates a vector of time indices, with one element for each time index on which the series was observed.

The `deltat()`

function returns the fixed time interval between observations and the `frequency()`

function returns the number of observations per unit time. Finally, the `cycle()`

function returns the position in the cycle of each observation.

In this exercise, you'll practice applying these functions to the `AirPassengers`

dataset, which reports the monthly total international airline passengers (in thousands) from 1949 to 1960.

Instructions

**100 XP**

- Begin by plotting the
`AirPassengers`

data using a simple call to`plot()`

. - Next, list the first and last time observations in
`AirPassengers`

using`start()`

and`end()`

, respectively. - Finally, gain some additional insight into this dataset by using the
`time()`

,`deltat()`

,`frequency()`

, and`cycle()`

commands`AirPassengers`

.