R: Variance of a collection of spectra

s_var {photobiology}

R Documentation

Variance of a collection of spectra

Description

A method to compute the variance of values across members of a collections of spectra. Computes the variance at each wavelength across all the spectra in the collection returning a spectral object.

Usage

s_var(x, na.rm, ...)

## Default S3 method:
s_var(x, na.rm = FALSE, ...)

## S3 method for class 'filter_mspct'
s_var(x, na.rm = FALSE, ...)

## S3 method for class 'source_mspct'
s_var(x, na.rm = FALSE, ...)

## S3 method for class 'response_mspct'
s_var(x, na.rm = FALSE, ...)

## S3 method for class 'reflector_mspct'
s_var(x, na.rm = FALSE, ...)

## S3 method for class 'calibration_mspct'
s_var(x, na.rm = FALSE, ...)

## S3 method for class 'cps_mspct'
s_var(x, na.rm = FALSE, ...)

## S3 method for class 'raw_mspct'
s_var(x, na.rm = FALSE, ...)

Arguments

`x`	An R object. Currently this package defines methods for collections of spectral objects.
`na.rm`	logical. A value indicating whether NA values should be stripped before the computation proceeds.
`...`	Further arguments passed to or from other methods.

Details

Variance method for collections of spectra. Computes the variance at each wavelength across all the spectra in the collection.

Value

If x is a collection spectral of objects, such as a "filter_mspct" object, the returned object is of class "generic_spct", containing the variance among the spectra at each wavelength in a column with name ending in ".var".

Methods (by class)

s_var(default):
s_var(filter_mspct):
s_var(source_mspct):
s_var(response_mspct):
s_var(reflector_mspct):
s_var(calibration_mspct):
s_var(cps_mspct):
s_var(raw_mspct):

Note

Omission of NAs is done separately at each wavelength. Interpolation is not applied, so all spectra in x must share the same set of wavelengths.

Objects of classes raw_spct and cps_spct can contain data from multiple scans. This functions are implemented for these classes only for the case when all member spectra contain data for a single scan, or spliced into a single column in the case of cps_spct members.