Combine topic modeling and sentiment analysis to identify individual students' gaps, and highlight their strengths and weaknesses across predefined competency domains and professional activities.

Explore continuous, date and categorical variables. 'sumvar' aims to bring the ease and simplicity of the "sum" and "tab" functions from 'stata'.

Make interactive 'd3.js' sequence sunburst diagrams in R with the
    convenience and infrastructure of an 'htmlwidget'.

Get sun position, sunlight phases (times for sunrise, sunset, dusk, etc.),
        moon position and lunar phase for the given location and time. Most calculations are based on the 
        formulas given in Astronomy Answers articles about position of the sun and the planets : 
        <https://www.aa.quae.nl/en/reken/zonpositie.html>.

Compute the position of the sun, and local solar time using Meeus'
    formulae. Compute day and/or night length using different
    twilight definitions or arbitrary sun elevation angles. This package is 
    part of the 'r4photobiology' suite, Aphalo, P. J. (2015)
    <doi:10.19232/uv4pb.2015.1.14>. Algorithms from Meeus (1998, ISBN:0943396611).

Survival analysis for unbalanced clusters using Archimedean copulas (Prenen et al. (2016) <DOI:10.1111/rssb.12174>).

Suns-Voc (or Isc-Voc) curves can provide the current-voltage (I-V) characteristics of the
    diode of photovoltaic cells without the effect of series resistance.
    Here, Suns-Voc curves can be constructed with outdoor time-series I-V
    curves [1,2,3] of full-size photovoltaic (PV) modules instead of having to be measured in the lab.
    Time series of four different power loss modes can be calculated based on obtained Isc-Voc curves.
    This material is based upon work supported by the U.S. Department of
    Energy's Office of Energy Efficiency and Renewable Energy (EERE) under
    Solar Energy Technologies Office (SETO) Agreement Number DE-EE0008172. 
    Jennifer L. Braid is supported by the U.S. Department of Energy (DOE) Office of 
    Energy Efficiency and Renewable Energy administered by the Oak Ridge 
    Institute for Science and Education (ORISE) for the DOE. 
    ORISE is managed by Oak Ridge Associated Universities (ORAU) under DOE
    contract number DE-SC0014664. 
    [1] Wang, M. et al, 2018. 
    <doi:10.1109/PVSC.2018.8547772>. 
    [2] Walters et al, 2018
    <doi:10.1109/PVSC.2018.8548187>. 
    [3] Guo, S. et al, 2016. 
    <doi:10.1117/12.2236939>.