As recently as a few months ago, R used a form of "reference counting" which only allowed three values in the counter: 0, 1, and 2 [1]. This might be caused by

As recently as a few months ago, R used a form of "reference counting" which only allowed three values in the counter: 0, 1, and 2 [1]. This might be caused by unusual ancestry or it might not, but it's hard to stop saying R sucks when it does that in 2014. [1] http://stackoverflow.com/a/25384396/4323 http://stackoverflow.com/a/25384396/4323