photobiology (version 0.10.6)

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 = `

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.

Examples

# NOT RUN {
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")

# }