photobiology 0.9.20

The main changes from version 0.9.19, the most recent CRAN release, are:

  • To improve clarity of user code, define wrappers for methods max(), min(), range(), midpoint(), and spread() with names with wl_ prepended (e.g. wl_max()).
  • Rename method spread() to expanse() and deprecate use of spread(). In the case of wl_expanse() and expanse() the new names prevent a name clash with tidyr::spread().
  • Redefine all ‘as.’ class-coercion functions into generic methods and add specialisations. Default behaviour remains unchanged.
  • Add class-coercion methods to and from matrix (and transfer corresponding functions from package ‘photobiologyInOut’).
  • Add function relative_AM() to compute relative air mass from sun elevation.
  • Add functions for calculation of saturated water vapour pressure from air temperature water_vp_sat() and dew point from water vapour pressure water_dp().

Documentation web site at includes all help pages, with output from all examples, and vignettes in HTML format.

NOTE: The updated package can be installed from CRAN.

Please raise issues concerning bugs or enhancements to this package through Bitbucket


This update is an attempt to fix a bug preventing the package from loading under OS X and Linux. Not yet tested, as there seem to be additional problems under OS X at least. The remaining problem seems to be related to some component of OmniDriver being incompatible with OS X.

This is an interim patch which will be replaced in due time with a version tested under multiple OSs rather than only under Windows 10.

This package can be downloaded from the repository at this site, not from CRAN. It has system prerequisites described in the online documentation at

Please raise issues concerning bugs or enhancements to this package through Bitbucket at