Function that converts transmittance (fraction) into absorptance (fraction). If reflectance (fraction) is available, it also allows conversions between internal and total absorptance.
T2Afr(x, action, byref, clean, ...)# S3 method for default
T2Afr(x, action = NULL, byref = FALSE, clean = FALSE, ...)
# S3 method for numeric
T2Afr(x, action = NULL, byref = FALSE, clean = FALSE, Rfr = NA_real_, ...)
# S3 method for filter_spct
T2Afr(x, action = "add", byref = FALSE, clean = FALSE, ...)
# S3 method for object_spct
T2Afr(x, action = "add", byref = FALSE, clean = FALSE, ...)
# S3 method for filter_mspct
T2Afr(
x,
action = "add",
byref = FALSE,
clean = FALSE,
...,
.parallel = FALSE,
.paropts = NULL
)
# S3 method for object_mspct
T2Afr(
x,
action = "add",
byref = FALSE,
clean = FALSE,
...,
.parallel = FALSE,
.paropts = NULL
)
A copy of x
with a column Afr
added and other columns
possibly deleted except for w.length
. If action = "replace"
,
in all cases, the redundant columns are removed, even when
column Afr
was present in the argument passed to x
.
an R object.
character Allowed values "replace"
and "add"
.
logical indicating if new object will be created by reference
or by copy of x
.
logical replace off-boundary values before conversion.
not used in current version.
numeric vector. Spectral reflectance o reflectance factor.
Set to zero if x
is internal reflectance,
if TRUE, apply function in parallel, using parallel backend provided by foreach
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.
T2Afr(default)
: Default method for generic function
T2Afr(numeric)
: Default method for generic function
T2Afr(filter_spct)
: Method for filter spectra
T2Afr(object_spct)
: Method for object spectra
T2Afr(filter_mspct)
: Method for collections of filter spectra
T2Afr(object_mspct)
: Method for collections of object spectra
Absorptance, internal transmittance and total reflectance when expressed as fractions, add up to one:
$$1 = \alpha + \tau + \rho$$
where, \(\alpha\) is absorptance, \(\tau\) is internal transmittance and \(\rho\) is total reflectance. If any two of these quantities are known, the third one can be computed from them.
On the other hand:
$$1 = \alpha\prime + T$$
where, \(\alpha\prime = \alpha + \rho\), measured together. In this case, there is not enough information available to compute \(\alpha\).
Thus, method T2Afr()
computes
either \(\alpha\) or \(\alpha\prime\),
depending on whether \(\tau\) or \(T\) are contained in the argument
passed to x
, but neither of them when only \(\tau\) is known. To
know which quantity has been computed, use getTfrType()
to query
whether the computations were based on \(\tau\) or \(T\).
The R names used are: Tfr
for \(\tau\) and \(T\) are Tfr
,
Afr
for \(\alpha\) and \(\alpha\prime\), and Rfr
for
\(rho\). The distinction between \(\tau\) and \(T\) and
between \(\alpha\) and \(\alpha\prime\) is made based on metadata
attributes.
Other quantity conversion functions:
A2T()
,
Afr2T()
,
T2A()
,
any2T()
,
as_quantum()
,
e2q()
,
e2qmol_multipliers()
,
e2quantum_multipliers()
,
q2e()