[R] editing ".Internal" functions

Prof Brian Ripley ripley at stats.ox.ac.uk
Wed Aug 23 19:21:09 CEST 2006

On Wed, 23 Aug 2006, B. Chasco wrote:

> There is a function called arrows() which is an .Internal function.  How 
> difficult is it to modify that function to return the xy coordinates for 
> the line "segments" that make up the arrowhead?

That depends on your 'core competencies'.  You have the source, which is 
in file src/main/plot.c (and GArrow in src/main/graphics.c).  I am not 
sure I understand your question, as arrows() is plural and draws multiple 
arrows with 0/1/2 heads each.  Also, the 'xy coordinates' are to be in 
which coordinate system, and you do realize that the sizes in user 
coordinates change if you resize the plot?

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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