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time Sampling Times of Time Series

Description

time creates the vector of times at which a time series was sampled.

cycle gives the positions in the cycle of each observation.

frequency returns the number of samples per unit time and deltat the time interval between observations (see ts).

Usage

time(x, ...)
## Default S3 method:
time(x, offset = 0, ...)

cycle(x, ...)
frequency(x, ...)
deltat(x, ...)

Arguments

x	a univariate or multivariate time-series, or a vector or matrix.
offset	can be used to indicate when sampling took place in the time unit. 0 (the default) indicates the start of the unit, 0.5 the middle and 1 the end of the interval.
...	extra arguments for future methods.

Details

These are all generic functions, which will use the tsp attribute of x if it exists. time and cycle have methods for class ts that coerce the result to that class.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

ts, start, tsp, window.

date for clock time, system.time for CPU usage.

Examples

require(graphics)

cycle(presidents)
# a simple series plot
plot(as.vector(time(presidents)), as.vector(presidents), type = "l")