In R it is possible to customise the appearance of a dendrogram and set a custom start character for the last branches. According to the documentation:

In some environments, using ' will provide much nicer looking output, than the historical default `.

Emacs ESS does just this and, in ess-s-l.el, sets the option str.dendrogram.last to a single quote. It is a sort of strict requirement, in fact, contrary to the Emacs ESS philosophy (where everything can be customised), this setting is hardcoded in ess-s-l.el and is difficult to override. Therefore I assume that Emacs is one of those environments where single quotes look much nicer than backticks.

Anyway, in my current Windows Emacs version, backticks look perfect and I am going (trying) to get rid of it.
However I wonder whether there is some situation where backticks might display poorly or it is a problem showed in some old Emacs version.


Are you asking how to set str.dendrogram.last to "`"? That can be done from R using the last.str argument to str():

str(dend1, max = 2, last.str =  "`") 

or, it can be set using the function

options(str.dendrogram.last = "`") 

You can add the options() call to your .Rprofile file to have it loaded automatically, which should over-ride the setting imposed by ESS.

Whether this displays poorly or not will depend on the font you are using.

  • Actually I just would like to understand why they set the single quotation. I think there should be a specific reason to override R defaults. – antonio Oct 11 '16 at 17:22
  • The ESS group is pretty active, you could ask them directly. – Tyler Oct 11 '16 at 17:46

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