Piano chords in R with the R package 'pichor'

I am learning how to play piano. In that process, I needed charts with piano chords. I know it is good practise to construct the chords manually, figure out the inversions and so on, but I found that some aspects of learning were improved with a chord chart. I searched the (entire!) internet, and struggled to find good, customisable charts. Thus I had to make something myself: pichor, an R package for making and working with piano chords in R.

Major update of Ryacas (R Interface to the Yacas Computer Algebra System)

Update Aug 27, 2019: Minor change in how equations are solved (from version We (Søren Højsgaard and I) are preparing a new major release of Ryacas (GitHub). It will have a new interface to yacas that is thinner, cleaner and more robust. It relies on yacas’s RForm() function rather than an OpenMath XML interface. It also means that the API has changed in Ryacas: new functions are introduced and old ones deprecated.