# yearmon

From zoo v0.9-9
by Achim Zeileis

##### An Index Class for Monthly Data

`"yearmon"`

is a class for representing monthly data.

- Keywords
- ts

##### Usage

`yearmon(x)`

##### Arguments

- x
- numeric (interpreted as being
in years ).

##### Details

The yearmon class is used to represent monthly data. Internally it holds
the data as year plus 0 for January, 1/12 for February, 2/12 for March
and so on in order that its internal representation is the same as
`ts`

class with `frequency = 12`

. If `x`

is not in this
format it is rounded via `floor(12*x + .0001)/12`

.
There are coercion methods available for various classes including:
default coercion to `"yearmon"`

(which coerces to `"numeric"`

first)
and coercion from `"yearmon"`

to `"Date"`

(see below), `"POSIXct"`

,
`"POSIXlt"`

, `"numeric"`

, `"character"`

.

##### Value

- Returns its argument converted to class
`yearmon`

.

##### See Also

##### Examples

```
x <- yearmon(2000 + seq(0, 23)/12)
x
# returned Date is the fraction of the way through
# the period given by frac (= 0 by default)
as.Date(x)
as.Date(x, frac = 1)
as.POSIXct(x)
z <- zoo(rnorm(24), x, frequency = 12)
z
as.ts(z)
```

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

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