R: Energy:photon ratio

eq_ratio {photobiology} | R Documentation

## 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, wb.trim, use.cached.mult, use.hinges, ...)

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

    ## S3 method for class 'source_spct'
    eq_ratio(spct, w.band = NULL,
      wb.trim = getOption("photobiology.waveband.trim", default = TRUE),
      use.cached.mult = FALSE,
      use.hinges = getOption("photobiology.use.hinges"), ...)

    ## S3 method for class 'source_mspct'
    eq_ratio(spct, w.band = NULL,
      wb.trim = getOption("photobiology.waveband.trim", default = TRUE),
      use.cached.mult = FALSE,
      use.hinges = getOption("photobiology.use.hinges"), ..., attr2tb = NULL,
      idx = !is.null(names(spct)), .parallel = FALSE, .paropts = NULL)

### Arguments

`spct` | source_spct.
`w.band` | waveband or list of waveband objects.
`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).
`attr2tb` | character vector, see `add_attr2tb` for the syntax for `attr2tb` passed as is to formal parameter `col.names`.
`idx` | logical whether to add a column with the names of the elements of spct
`.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.

### 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)

- `default`: Default for generic function

- `source_spct`: Method for `source_spct` objects

- `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_ratio`, `q_ratio`, `qe_ratio`

### Examples

    eq_ratio(sun.spct, new_waveband(400,700))

[Package photobiology version 0.9.21 Index]