# index

From zoo v0.9-9
by Achim Zeileis

##### Extracting/Replacing the Index of Objects

Generic functions for extracting the index of an object and replacing it.

- Keywords
- ts

##### Usage

```
index(x, ...)
index(x) <- value
```

##### Arguments

- x
- an object.
- ...
- further arguments passed to methods.
- value
- an ordered vector of the same length
as the
`"index"`

attribute of`x`

.

##### Details

`index`

is a generic function for extracting the index
of objects, currently it has a default method and a method
for `zoo`

objects which is the same as the
`time`

method for `zoo`

objects.
Another pair of generic functions provides replacing
the `index`

or `time`

attribute.
Methods are available for `"zoo"`

objects only, see examples below.

The start and end of the index/time can be queried by using
the methods of `start`

and `end`

.

##### See Also

##### Examples

```
x.date <- as.Date(paste(2003, 2, c(1, 3, 7, 9, 14), sep = "-"))
x <- zoo(rnorm(5), x.date)
## query index/time of a zoo object
index(x)
time(x)
## change class of index from Date to POSIXct
## relative to current time zone
x
index(x) <- as.POSIXct(format(time(x)),tz="")
x
## replace index/time of a zoo object
index(x) <- 1:5
x
time(x) <- 6:10
x
## query start and end of a zoo object
start(x)
end(x)
## query index of a usual matrix
xm <- matrix(rnorm(10), ncol = 2)
index(xm)
```

*Documentation reproduced from package zoo, version 0.9-9, License: GPL*

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