interpolate: interpolate spectra

Description

interpolate along a 1-parameter path of spectra

Usage

# S3 method for colorSpec
interpolate( x, p, pout, pname=deparse(substitute(p)) )

Value

interpolate(x) returns a colorSpec object y

with a spectrum for each value in pout. The organization of y is 'df.row', and extradata(y) has a single column which is a copy of pout. The name of the column is pname. The names in specnames(y) are <pname>=<pout>. Other properties of y, e.g. wavelength, quantity, ..., are the same as x.

In case of ERROR, the function returns NULL.

Arguments

x: a colorSpec object, typically with multiple spectra
p: a numeric vector with length(p)==numSpectra(x). The value p[i] is associated with the i'th spectrum in x.
pout: a numeric vector of parameter values at which interpolation of the spectra in x take place
pname: the name of the parameter p

Details

Each spectrum in x can be thought of as a point in a high-dimensional space, and each point has a real-valued parameter associated with it. The function performs natural spline interpolation on these points, one coordinate at a time. For each wavelength value it calls spline with method='natural'.

Examples

Run this code

path = system.file( "extdata/stains/PhenolRed-Fig7.txt", package="colorSpec" )
wave = 350:650
phenolred = readSpectra( path, wavelength=wave )
pH = as.numeric( sub( '[^0-9]+([0-9]+)$', '\\1', specnames(phenolred) ) )
pHvec = seq(min(pH),max(pH),by=0.05)
phenolinterp = interpolate( phenolred, pH, pHvec )