Convert the

Function to set the "Tfr.type" attribute and simultaneously convert the spectral data to correspond to the new type.

Usage

convertTfrType(x, Tfr.type = NULL)

Arguments

x: a filter_spct, object_spct, filter_mspct or object_mspct object.
Tfr.type: character One of "internal" or "total".

Value

x if possible, with the value of the "Tfr.type" attribute modified and the values stored in the Tfr variable converted to the new quantity.

Details

Internal transmittance, $\tau$, uses as reference the light entering the object while total transmittance, $T$, takes the incident light as reference. The conversion is possible only if total reflectance, $\rho$, is known. Either as spectral data in an object_spct object, a filter_spct object that is "under-the-hood" an object_spct, or if a fixed reflectance factor applicable to all wavelengths is stored in the filter.properties attribute of the filter_spct object.

Conversions are computed as:

$$\tau = \frac{T - \rho}{1 - \rho}$$

and

$$T = \tau * (1 - \rho) + \rho$$

For the conversion to take place the object passed as argument to x, must contain a column with transmittance data, named Tfr. Any necessary conversion from absorbance A or from Afr into transmittance, must be done before calling convertTfrType().

Note

if x is not a filter_spct object, x is returned unchanged. If x does not have the "filter.properties" attribute set if it is missing data, x is returned with Tfr set to NA values.

Examples

getTfrType(polyester.spct)
#> [1] "total"
filter_properties(polyester.spct)
#> Rfr (/1): 0.074, thickness (mm): 0.125, attenuation mode: absorption.
convertTfrType(polyester.spct, Tfr.type = "internal")
#> Object: filter_spct [454 x 2]
#> Wavelength range 240-800 nm, step 1-4 nm 
#> Label: Polyester, clear film, 0.000125 m thick, Autostat CT5 from McDermit Autotype; new 
#> Rfr (/1): 0.074, thickness (mm): 0.125, attenuation mode: absorption.
#> Variables:
#>  w.length: Wavelength [nm]
#>  Tfr: Internal spectral transmittance [/1] 
#> --
#> # A tibble: 454 × 2
#>    w.length     Tfr
#>       <int>   <dbl>
#>  1      240 0.00521
#>  2      241 0.00501
#>  3      242 0.00482
#>  4      244 0.00447
#>  5      246 0.00432
#>  6      248 0.00432
#>  7      252 0.00417
#>  8      256 0.00355
#>  9      258 0.00324
#> 10      259 0.00324
#> # ℹ 444 more rows

Convert the "Tfr.type" attribute