The `[`

-method extracts parts of an
`"sts"`

object
using row (time) and column (unit) indices.

```
# S4 method for sts
[(x, i, j, ..., drop)
```

## Arguments

- x
an object of class `"sts"`

.

- i
row index (integer or logical vector).

- j
column index (character, integer, or logical vector).

- ...,drop
unused (arguments of the generic).

Dimensions are never dropped.

##
Value

an object of class `"sts"`

.

##
Details

Row indices are used to select a subset of the original time period.
The `start`

and `epoch`

slots of the time series are
adjusted accordingly.
A warning is issued if an irregular integer sequence is used to
extract rows, e.g., `x[c(1,2,4),]`

, which could destroy the
structure of the time series (`freq`

).

Column indices work as usual when indexing matrices,
so may select units by name, position or a vector of booleans.
When subsetting columns, population fractions are recomputed if and
only if `x`

is no `multinomialTS`

and already contains
population fractions.

`NA`

indices are not supported, negative indices are.

Note that a `[<-`

method (i.e., subassignment) is not implemented.

##
Examples

```
data("ha.sts")
haagg <- aggregate(ha.sts, nfreq=13)
plot(haagg[, 3]) # Single series
plot(haagg[1:30, 3]) # Somewhat shorter
#Counts at time 20
plot(haagg[20, ], type = observed ~ unit)
```