eq_ratio: Energy:photon ratio

In photobiology: Photobiological Calculations

Energy:photon ratio

Description

This function returns the energy to mole of photons ratio for each waveband and a light source spectrum.

Usage

eq_ratio(spct, w.band, scale.factor, wb.trim, use.cached.mult, use.hinges, ...)

## Default S3 method:
eq_ratio(spct, w.band, scale.factor, wb.trim, use.cached.mult, use.hinges, ...)

## S3 method for class 'source_spct'
eq_ratio(
  spct,
  w.band = NULL,
  scale.factor = 1,
  wb.trim = getOption("photobiology.waveband.trim", default = TRUE),
  use.cached.mult = FALSE,
  use.hinges = NULL,
  naming = "short",
  name.tag = ifelse(naming != "none", "[e:q]", ""),
  ...
)

## S3 method for class 'source_mspct'
eq_ratio(
  spct,
  w.band = NULL,
  scale.factor = 1,
  wb.trim = getOption("photobiology.waveband.trim", default = TRUE),
  use.cached.mult = FALSE,
  use.hinges = NULL,
  naming = "short",
  name.tag = ifelse(naming != "none", "[e:q]", ""),
  ...,
  attr2tb = NULL,
  idx = "spct.idx",
  .parallel = FALSE,
  .paropts = NULL
)

Arguments

spct	source_spct.
w.band	waveband or list of waveband objects.
scale.factor	numeric vector of length 1, or length equal to that of w.band. Numeric multiplier applied to returned values.
wb.trim	logical if TRUE wavebands crossing spectral data boundaries are trimmed, if FALSE, they are discarded.
use.cached.mult	logical Flag telling whether multiplier values should be cached between calls.
use.hinges	logical Flag indicating whether to insert "hinges" into the spectral data before integration so as to reduce interpolation errors at the boundaries of the wavebands.
...	other arguments (possibly used by derived methods).
naming	character one of "long", "default", "short" or "none". Used to select the type of names to assign to returned value.
name.tag	character Used to tag the name of the returned values.
attr2tb	character vector, see add_attr2tb for the syntax for attr2tb passed as is to formal parameter col.names.
idx	character Name of the column with the names of the members of the collection of spectra.
.parallel	if TRUE, apply function in parallel, using parallel backend provided by foreach
.paropts	a list of additional options passed into the foreach function when parallel computation is enabled. This is important if (for example) your code relies on external data or packages: use the .export and .packages arguments to supply them so that all cluster nodes have the correct environment set up for computing.

Details

The ratio is based on one photon irradiance and one energy irradiance, both computed for the same waveband.

\frac{I(s, wb)}{Q(s, wb)}

Value

Computed values are ratios between energy irradiance and photon irradiance for a given waveband. A named numeric vector in the case of methods for individual spectra, with one value for each waveband passed to parameter w.band. A data.frame in the case of collections of spectra, containing one column for each waveband object, an index column with the names of the spectra, and optionally additional columns with metadata values retrieved from the attributes of the member spectra.

By default values are only integrated, but depending on the argument passed to parameter quantity they can be re-expressed as relative fractions or percentages. In the case of vector output, names attribute is set to the name of the corresponding waveband unless a named list is supplied in which case the names of the list members are used, with "[e:q]" prepended. Units [J mol-1].

Methods (by class)

• eq_ratio(default): Default for generic function

• eq_ratio(source_spct): Method for source_spct objects

• eq_ratio(source_mspct): Calculates energy:photon from a source_mspct object.

Note

The last two parameters control speed optimizations. The defaults should be suitable in most cases. If you will use repeatedly the same SWFs on many spectra measured at exactly the same wavelengths you may obtain some speed up by setting use.cached.mult=TRUE. However, be aware that you are responsible for ensuring that the wavelengths are the same in each call, as the only test done is for the length of the w.length vector.

See Also

Other photon and energy ratio functions: e_fraction(), e_ratio(), q_fraction(), q_ratio(), qe_ratio()

Examples

eq_ratio(sun.spct,
         waveband(c(400,700), wb.name = "White")) # J mol-1
eq_ratio(sun.spct,
         waveband(c(400,700), wb.name = "White"),
         scale.factor = 1e-6) # J umol-1

photobiology documentation built on Oct. 21, 2023, 1:06 a.m.