# rollmean

From zoo v1.7-0
by Achim Zeileis

##### Rolling Means/Maximums/Medians

Generic functions for computing rolling means, maximums and medians of ordered observations.

- Keywords
- ts

##### Usage

```
rollmean(x, k, fill = if (na.pad) NA, na.pad = FALSE,
align = c("center", "left", "right"), ...)
rollmeanr(..., align = "right")
rollmax(x, k, fill = if (na.pad) NA, na.pad = FALSE,
align = c("center", "left", "right"), ...)
rollmaxr(..., align = "right")
rollmedian(x, k, fill = if (na.pad) NA, na.pad = FALSE,
align = c("center", "left", "right"), ...)
rollmedianr(..., align = "right")
```

##### Arguments

- x
- an object (representing a series of observations).
- k
- integer width of the rolling window. Must be odd for
`rollmedian`

. - fill
- a three-component vector or list (recycled otherwise) providing
filling values at the left/within/to the right of the data range.
See the
`fill`

argument of`na.fill`

for details. - na.pad
- deprecated. Use
`fill = NA`

instead of`na.pad = TRUE`

. - align
- character specifying whether the index of the result should be left- or right-aligned or centered (default) compared to the rolling window of observations.
- ...
- Further arguments passed to methods.

##### Details

These functions compute rolling means, maximums and medians respectively
and are thus similar to `rollapply`

but are
optimized for speed.

Currently, there are methods for `"zoo"`

and `"ts"`

series and
default methods. The default method of `rollmedian`

is an interface to `runmed`

.
The default method of `rollmean`

does not handle inputs that contain
`NA`

s. In such cases, use `rollapply`

instead.

##### Value

- An object of the same class as
`x`

with the rolling mean/max/median.

##### See Also

##### Examples

```
x.Date <- as.Date(paste(2004, rep(1:4, 4:1), sample(1:28, 10), sep = "-"))
x <- zoo(rnorm(12), x.Date)
rollmean(x, 3)
rollmax(x, 3)
rollmedian(x, 3)
xm <- zoo(matrix(1:12, 4, 3), x.Date[1:4])
rollmean(xm, 3)
rollmax(xm, 3)
rollmedian(xm, 3)
rollapply(xm, 3, mean) # uses rollmean
rollapply(xm, 3, function(x) mean(x)) # does not use rollmean
```

*Documentation reproduced from package zoo, version 1.7-0, License: GPL-2*

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