first | R Documentation |

Generic functions to return the first or last elements or rows of a vector or two-dimensional data object.

```
first(x, ...)
## Default S3 method:
first(x, n = 1, keep = FALSE, ...)
## S3 method for class 'xts'
first(x, n = 1, keep = FALSE, ...)
last(x, ...)
## Default S3 method:
last(x, n = 1, keep = FALSE, ...)
## S3 method for class 'xts'
last(x, n = 1, keep = FALSE, ...)
```

`x` |
An object. |

`...` |
Arguments passed to other methods. |

`n` |
Number of observations to return. |

`keep` |
Should removed values be kept as an attribute on the result? |

A more advanced subsetting is available for zoo objects with indexes inheriting from POSIXt or Date classes.

Quickly and easily extract the first or last `n`

observations of an object.
When `n`

is a number, these functions are similar to `head()`

and
`tail()`

, but only return the *first* or *last* observation by default.

`n`

can be a character string if `x`

is an xts object or coerceable to xts.
It must be of the form ‘n period’, where 'n' is a numeric value
(1 if not provided) describing the number of periods to return. Valid
periods are: secs, seconds, mins, minutes, hours, days, weeks, months,
quarters, and years.

The 'period' portion can be any frequency greater than or equal to the
frequency of the object's time index. For example, `first(x, "2 months")`

will return the first 2 months of data even if `x`

is hourly frequency.
Attempts to set 'period' to a frequency less than the object's frequency
will throw an error.

`n`

may be positive or negative, whether it's a number or character string.
When `n`

is positive, the functions return the obvious result. For example,
`first(x, "1 month")`

returns the first month's data. When `n`

is negative,
all data *except* first month's is returned.

Requesting more data than is in `x`

will throw a warning and simply return
`x`

.

A subset of elements/rows of the original data.

Jeffrey A. Ryan

```
first(1:100)
last(1:100)
data(LakeHuron)
first(LakeHuron,10)
last(LakeHuron)
x <- xts(1:100, Sys.Date()+1:100)
first(x, 10)
first(x, '1 day')
first(x, '4 days')
first(x, 'month')
last(x, '2 months')
last(x, '6 weeks')
```

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.