R: Fluence

fluence {photobiology} | R Documentation

## Fluence

### Description

Energy or photon fluence for one or more wavebands of a light source spectrum and a duration of exposure.

### Usage

    fluence(spct, w.band, unit.out, exposure.time, wb.trim, use.cached.mult,
      use.hinges, allow.scaled, ...)

    ## Default S3 method:
    fluence(spct, w.band, unit.out, exposure.time, wb.trim,
      use.cached.mult, use.hinges, allow.scaled, ...)

    ## S3 method for class 'source_spct'
    fluence(spct, w.band = NULL,
      unit.out = getOption("photobiology.radiation.unit", default = "energy"),
      exposure.time, wb.trim = getOption("photobiology.waveband.trim", default =
      TRUE), use.cached.mult = getOption("photobiology.use.cached.mult", default =
      FALSE), use.hinges = NULL, allow.scaled = FALSE, ...)

    ## S3 method for class 'source_mspct'
    fluence(spct, w.band = NULL,
      unit.out = getOption("photobiology.radiation.unit", default = "energy"),
      exposure.time, wb.trim = getOption("photobiology.waveband.trim", default =
      TRUE), use.cached.mult = getOption("photobiology.use.cached.mult", default =
      FALSE), use.hinges = NULL, allow.scaled = FALSE, ..., attr2tb = NULL,
      idx = !is.null(names(spct)), .parallel = FALSE, .paropts = NULL)

### Arguments

`spct` | an R object.
`w.band` | a list of `waveband` objects or a `waveband` object.
`unit.out` | character string with allowed values "energy", and "photon", or its alias "quantum".
`exposure.time` | lubridate::duration object.
`wb.trim` | logical if TRUE wavebands crossing spectral data boundaries are trimmed, if FALSE, they are discarded.
`use.cached.mult` | logical indicating 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.
`allow.scaled` | logical indicating whether scaled or normalized spectra as argument to spct are flagged as an error.
`...` | 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

One numeric value for each waveband with no change in scale factor, with name attribute set to the name of each waveband unless a named list is supplied in which case the names of the list elements are used. The time.unit attribute is copied from the spectrum object to the output. Units are as follows: If time.unit is second, [W m-2 nm-1] -> [mol s-1 m-2] If time.unit is day, [J d-1 m-2 nm-1] -> [mol d-1 m-2]

### Methods (by class)

- `default`: Default for generic function

- `source_spct`: Calculate photon fluence from a `source_spct` object and the duration of the exposure

- `source_mspct`: Calculates fluence 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 irradiance functions: `e_fluence`, `e_irrad`, `irrad`, `q_fluence`, `q_irrad`

### Examples

    library(lubridate)
    fluence(sun.spct,
            w.band = waveband(c(400,700)),
            exposure.time = lubridate::duration(3, "minutes") )

[Package photobiology version 0.9.21 Index]