Rescale values to lie in a given range

Description

This is helpful in e.g. developing a colour scale for an image plot. It is not necessary that rlow be less than rhigh, and in fact reversing them is a good way to get a reversed colour scale for a plot.

Usage

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rescale(x, xlow, xhigh, rlow = 0, rhigh = 1, clip = TRUE)

Arguments

x

a numeric vector.

xlow

x value to correspond to rlow. If not given, it will be calculated as the minimum value of x

xhigh

x value to correspond to rhigh. If not given, it will be calculated as the maximum value of x

rlow

value of the result corresponding to x equal to xlow.

rhigh

value of the result corresponding to x equal to xhigh.

clip

logical, set to TRUE to clip the result to the range spanned by rlow and rhigh.

Value

A new vector, which has minimum lim[1] and maximum lim[2].

Author(s)

Dan Kelley

Examples

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library(oce)
# Fake tow-yow data
t <- seq(0, 600, 5)
x <- 0.5 * t
z <- 50 * (-1 + sin(2 * pi * t / 360))
T <- 5 + 10 * exp(z / 100)
palette <- oce.colorsJet(100)
zlim <- range(T)
drawPalette(zlim=zlim, col=palette)
plot(x, z, type='p', pch=20, cex=3,
     col=palette[rescale(T, xlow=zlim[1], xhigh=zlim[2], rlow=1, rhigh=100)])

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