first: Select first element(s)

In rappster/selectr: Convience functions for selecting elements from R objects

Description

Selects the first n elements of an object.

Usage

first(x, ...)

Arguments

x	ANY-class. The object from which to select elements.
...	Further arguments passed to the respective methods that are being called

Value

Depends on the actual method being called

Methods

• first.default

• first.data.frame

Author(s)

Janko Thyson [e-mail]

References

http://github.com/rappster/selectr

See Also

first.default, first.data.frame

Examples

##------------------------------------------------------------------------------
## Vector //
##------------------------------------------------------------------------------

x <- letters
first(x)
first(x, 3)
first(x, 3, keep = TRUE)

## Conditions //
first(x, 30)
first(x, 30, strict = 1)
first(x, 30, strict = 2)
try(first(x, 30, strict = 3))

##------------------------------------------------------------------------------
## List //
##------------------------------------------------------------------------------

x <- as.list(letters)
first(x)
first(x, 3)
res <- first(x, 3, keep = TRUE)
attributes(res)

## Conditions //
first(x, 30)
first(x, 30, strict = 1)
first(x, 30, strict = 2)
try(first(x, 30, strict = 3))

##------------------------------------------------------------------------------
## Data frame //
##------------------------------------------------------------------------------

x <- data.frame(a= 1:5, b = letters[1:5], stringsAsFactors = FALSE)

## Rows:
first(x)
first(x, 3)
first(x, 3, keep = TRUE)

## Columns:
first(x, margin = 2)
first(x, 2, margin = 2)
first(x, 3, margin = 2)

first(x, margin = 2, drop = TRUE)
first(x, 2, margin = 2, drop = TRUE)

## Conditions:
first(x, 10)
first(x, 10, strict = 1)
first(x, 10, strict = 2)
try(first(x, 10, strict = 3))

first(x, 3, margin = 2)
first(x, 3, margin = 2, strict = 1)
first(x, 3, margin = 2, strict = 2)
try(first(x, 3, margin = 2, strict = 3))

rappster/selectr documentation built on May 26, 2019, 11:57 p.m.