photobiologyWavebands 0.5.1

PAR, or photosynthetically active radiation, as defined by McCree (1972) and used almost universaly in plant sciences is a biological spectral weighting function or BSWF that for spectral irradiance in photon based units takes one of two values for the weights: 0 or 1. So for computations of PAR photon irradiance (or PPFD) it is equivalent to integration over a range of wavelengths without application of a weighting function.

However, PAR, as defined by McCree, has a BSWF with weights that vary with wavelength when used to computed PAR (energy) irradiance, a quantity currently almost never used. Anyway the definition of the PAR()  waveband constructor in previous versions of the package was conceptually wrong, and has now been fixed. If anybody happened to compute PAR energy irradiance with earlier versions of the package, the results obtained were  not weighted. This non-weighted quantity has been in the old literature occasionally also called PAR, but is a “PAR” quantity based on a different defintion than McCree’s. In the new version the result from the same computation is weighted, and differs from the one computed using earlier versions to an extent that depends on the shape of the spectrum.

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photobiology 0.10.15

One of the features of the package for a long time has been automatic wavelength interpolation when needed in computations involving two spectra. However, until the current version this behaviour did not extend to operations summarizing multiple spectra stored as members of the same collection, as inconsistent wavelength values triggered an error.

This update to ‘photobiology’ enhances the compatibility of ‘ggspectra’ with spct objects that have been reduced in size by removal or “thinning” of intermediate wavelength values in rectilinear regions.

Spectra containing data for multiple spectra in long form were not well suported as members of mspct collection objects, i.e., some operations available for collections without such members were unsupported.

These changes also enhance the compatibilty of package ‘ggspectra’ with the presence of inconsistent wavelengths across members of collections of spectra.

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