photobiology: find_wls – R documentation

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find_wls

Find wavelength values in a spectrum

Description

Find wavelength values corresponding to a target y value in any spectrum. The name of the column of the spectral data to be used to match the target needs to be passed as argument unless the spectrum contains a single numerical variable in addition to "w.length".

Usage

find_wls(
  x,
  target = NULL,
  col.name.x = NULL,
  col.name = NULL,
  .fun = `<=`,
  interpolate = FALSE,
  idfactor = FALSE,
  na.rm = FALSE
)

Arguments

`x`	an R object
`target`	numeric value indicating the spectral quantity value for which wavelengths are to be searched and interpolated if need. The character strings "half.maximum" and "half.range" are also accepted as arguments.
`col.name.x`	character The name of the column in which to the independent variable is stored. Defaults to "w.length" for objects of class `"generic_spct"` or derived.
`col.name`	character The name of the column in which to search for the target value.
`.fun`	function A binary comparison function or operator.
`interpolate`	logical Indicating whether the nearest wavelength value in `x` should be returned or a value calculated by linear interpolation between wavelength values stradling the target.
`idfactor`	logical or character Generates an index column of factor type. If `idfactor = TRUE` then the column is auto named spct.idx. Alternatively the column name can be directly passed as argument to `idfactor` as a character string.
`na.rm`	logical indicating whether `NA` values should be stripped before searching for the target.

Value

A spectrum object of the same class as x with fewer rows, possibly even no rows. If FALSE is passed to interpolate a subset of x is returned, otherwise a new object of the same class containing interpolated wavelenths for the target value is returned.

Note

This function is used internally by method wls_at_target(), and these methods should be preferred in user code and scripts.

Examples

find_wls(white_led.source_spct)
find_wls(white_led.source_spct, target = "half.maximum")
find_wls(white_led.source_spct, target = 0.4)
find_wls(white_led.source_spct, target = 0.4, interpolate = TRUE)
find_wls(white_led.source_spct, target = c(0.3, 0.4))
find_wls(white_led.source_spct, target = c(0.3, 0.4), idfactor = "target")
find_wls(white_led.source_spct, target = c(0.3, 0.4), idfactor = TRUE)
find_wls(white_led.source_spct, target = c("HM", "HR"))
find_wls(white_led.source_spct, target = c("HM", "HR"), interpolate = TRUE)

led.df <- as.data.frame(white_led.source_spct)
find_wls(led.df, col.name = "s.e.irrad", col.name.x = "w.length")
find_wls(led.df, col.name = "s.e.irrad", col.name.x = "w.length",
         target = 0.4)
find_wls(led.df, col.name = "s.e.irrad", col.name.x = "w.length",
         target = c(0.3, 0.4))
find_wls(led.df, col.name = "s.e.irrad", col.name.x = "w.length",
         target = 0.4, idfactor = "target")

photobiology

Photobiological Calculations

v0.10.10

GPL (>= 2)

Authors

Pedro J. Aphalo [aut, cre] (<https://orcid.org/0000-0003-3385-972X>), Titta K. Kotilainen [ctb] (<https://orcid.org/0000-0002-2822-9734>), Glenn Davis [ctb], Agnese Fazio [ctb]

Initial release

2022-03-24