## Sampling Times of Time-Series

## Usage

    time(x, offset=0)
    start(x)
    end(x)
    frequency(x)
    tsp(x)

## Arguments

`x` | a time-series.

## Description

`time`, `start`, `end` and `frequency` are generic functions with a `default` and a `ts` method (see `methods`).

`time` creates the vector of times at which a time series was sampled. `offset` can be used to indicate when sampling took place in the time unit. `0` indicates the start of the unit, `0.5` the middle and `1` the end of the interval.

`start` and `end` extract the times the first and last observations were taken and `frequency` returns the number of samples per unit time.

`tsp(x)` returns the vector `c(start(x),end(x),frequency(x))`. It is included for compatibility with the S language.

## See Also

`ts`, `window` and `system.time` for CPU usage.

## Examples

    data(presidents)
    # a simple series plot
    plot(c(time(presidents)), c(presidents), type="l")

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