suggest enhancement to segments and arrows to facilitate horizontal and vertical segments
This isn't a one-way street, as it means that some erroneous calls will not be detected, and code written to take advantage of this will only work under R >= 2.10.0. I think we should probably insist that one of x1 and y1 is supplied: if both are omitted arrows() would give a warning, but segments() would not.
On Fri, 2 Oct 2009, Tim Hesterberg wrote:
I suggest a simple enhancement to segments() and arrows() to
facilitate drawing horizontal and vertical segments --
set default values for the second x and y arguments equal to the first set.
This is handy, especially when the expressions for coordinates are long.
Compare:
Segments:
< function (x0, y0, x1 = x0, y1 = y0, col = par("fg"), lty = par("lty"),
---
function (x0, y0, x1, y1, col = par("fg"), lty = par("lty"),
Arrows: < function (x0, y0, x1 = x0, y1 = y0, length = 0.25, angle = 30, code = 2, ---
function (x0, y0, x1, y1, length = 0.25, angle = 30, code = 2,
Tim Hesterberg
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