% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/acf.R
\name{Acf}
\alias{Acf}
\alias{Pacf}
\alias{Ccf}
\alias{taperedacf}
\alias{taperedpacf}
\title{(Partial) Autocorrelation and Cross-Correlation Function Estimation}
\usage{
Acf(
  x,
  lag.max = NULL,
  type = c("correlation", "covariance", "partial"),
  plot = TRUE,
  na.action = na.contiguous,
  demean = TRUE,
  ...
)

Pacf(
  x,
  lag.max = NULL,
  plot = TRUE,
  na.action = na.contiguous,
  demean = TRUE,
  ...
)

Ccf(
  x,
  y,
  lag.max = NULL,
  type = c("correlation", "covariance"),
  plot = TRUE,
  na.action = na.contiguous,
  ...
)

taperedacf(
  x,
  lag.max = NULL,
  type = c("correlation", "partial"),
  plot = TRUE,
  calc.ci = TRUE,
  level = 95,
  nsim = 100,
  ...
)

taperedpacf(x, ...)
}
\arguments{
\item{x}{a univariate or multivariate (not Ccf) numeric time series object
or a numeric vector or matrix.}

\item{lag.max}{maximum lag at which to calculate the acf. Default is
$10*log10(N/m)$ where $N$ is the number of observations and $m$ the number
of series. Will be automatically limited to one less than the number of
observations in the series.}

\item{type}{character string giving the type of acf to be computed. Allowed
values are \dQuote{\code{correlation}} (the default),
\dQuote{\code{covariance}} or \dQuote{\code{partial}}.}

\item{plot}{logical. If \code{TRUE} (the default) the resulting acf, pacf or
ccf is plotted.}

\item{na.action}{function to handle missing values. Default is
\code{\link[stats]{na.contiguous}}.  Useful alternatives are
\code{\link[stats]{na.pass}} and \code{\link{na.interp}}.}

\item{demean}{Should covariances be about the sample means?}

\item{...}{Additional arguments passed to the plotting function.}

\item{y}{a univariate numeric time series object or a numeric vector.}

\item{calc.ci}{If \code{TRUE}, confidence intervals for the ACF/PACF
estimates are calculated.}

\item{level}{Percentage level used for the confidence intervals.}

\item{nsim}{The number of bootstrap samples used in estimating the
confidence intervals.}
}
\value{
The \code{Acf}, \code{Pacf} and \code{Ccf} functions return objects
of class "acf" as described in \code{\link[stats]{acf}} from the stats
package. The \code{taperedacf} and \code{taperedpacf} functions return
objects of class "mpacf".
}
\description{
The function \code{Acf} computes (and by default plots) an estimate of the
autocorrelation function of a (possibly multivariate) time series. Function
\code{Pacf} computes (and by default plots) an estimate of the partial
autocorrelation function of a (possibly multivariate) time series. Function
\code{Ccf} computes the cross-correlation or cross-covariance of two
univariate series.
}
\details{
The functions improve the \code{\link[stats]{acf}},
\code{\link[stats]{pacf}} and \code{\link[stats]{ccf}} functions. The main
differences are that \code{Acf} does not plot a spike at lag 0 when
\code{type=="correlation"} (which is redundant) and the horizontal axes show
lags in time units rather than seasonal units.

The tapered versions implement the ACF and PACF estimates and plots
described in Hyndman (2015), based on the banded and tapered estimates of
autocovariance proposed by McMurry and Politis (2010).
}
\examples{

Acf(wineind)
Pacf(wineind)
\dontrun{
taperedacf(wineind, nsim=50)
taperedpacf(wineind, nsim=50)
}

}
\references{
Hyndman, R.J. (2015). Discussion of ``High-dimensional
autocovariance matrices and optimal linear prediction''. \emph{Electronic
Journal of Statistics}, 9, 792-796.

McMurry, T. L., & Politis, D. N. (2010). Banded and tapered estimates for
autocovariance matrices and the linear process bootstrap. \emph{Journal of
Time Series Analysis}, 31(6), 471-482.
}
\seealso{
\code{\link[stats]{acf}}, \code{\link[stats]{pacf}},
\code{\link[stats]{ccf}}, \code{\link{tsdisplay}}
}
\author{
Rob J Hyndman
}
\keyword{ts}
