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For scaling TikZ graphs, we use the scalebox instead of the optional parameter scale from the tikzpicture, since the font sizes and therefore the node sizes stay the same. Alternatively we could have inserted a line: "nodeR <- nodeR/scale".
"Some additional steps are needed for packages which make use of formal (S4-style) classes and methods (unless these are purely used internally). The package should have Depends: methods in its DESCRIPTION file and any classes and methods which are to be exported need to be declared in the NAMESPACE file." - http://cran.r-project.org/doc/manuals/R-exts.html#Namespaces-with-S4-classes-and-methods