R: Extend a Numerical Range by a Small Percentage

extendrange {grDevices}

R Documentation

Extend a Numerical Range by a Small Percentage

Description

Extends a numerical range by a small percentage, i.e., fraction, on both sides.

Usage

extendrange(x, r = range(x, na.rm = TRUE), f = 0.05)

Arguments

`x`	numeric vector; not used if `r` is specified.
`r`	numeric vector of length 2; defaults to the `range` of `x`.
`f`	positive number(s) specifying the fraction by which the range should be extended. If longer than one, `f[1]` is used on the left, and `f[2]` on the right.

Value

A numeric vector of length 2, r + c(-f1,f2) * diff(r), where f1 is f[1] and f2 is f[2] or f if it is of length one.

Examples

x <- 1:5
(r <- range(x))         # 1    5
extendrange(x)          # 0.8  5.2
extendrange(x, f= 0.01) # 0.96 5.04

## extend more to the right:
extendrange(x, f=c(.01,.03)) # 0.96 5.12

## Use 'r' if you have it already:
stopifnot(identical(extendrange(r = r),
                    extendrange(x)))