[R] Question about curve function

[peter dalgaard]

On Jun 6, 2011, at 11:22 , Prof Brian Ripley wrote:

> As a further example of the trickiness, the "function" method of plot() relies on curve(x, ...) being a request to plot the function x(x) against x.  I've added a comment to that effect to the help page.

Ouch. This springs to mind:

> fortune(106)

If the answer is parse() you should usually rethink the question.
   -- Thomas Lumley
      R-help (February 2005)


but curve() predates that insight by half a decade or more. It could probably do with a redesign, if anyone is up to it.

By the way, it really does work if the 2nd arg is an expression object (as opposed to an expression evaluating to an expression object):

do.call(curve,list(expression(x)))

or

cl <- quote(curve(x))
cl[[2]] <- expression(x)
eval(cl)

(The trouble with nonstandard evaluation is that it doesn't follow standard evaluation rules...)
 


-- 
Peter Dalgaard
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com