But the main point is where arguments are mixed together:
> debugonce(plot.default)
> plot(x=1:10, y=, 'l')
...
Browse[2]> missing(y)
[1] FALSE
Browse[2]> y
[1] "l"
Browse[2]> type
[1] "p"
I think that's what I fall over mostly: that named, empty arguments behave
entirely different from omitting them (", ,")
And I definitely agree we need a guru to explain it all to us (
Cheers, Emil Bode
On 30/11/2018, 15:35, "S Ellison" <s.elli...@lgcgroup.com> wrote:
> Yes, I think all of that is correct. But y _is_ missing in this sense:
> > plot(1:10, y=)
> > ...
> Browse[2]> missing(y)
Although I said what I meant by 'missing' vs 'not present', it wasn't
exactly what missing() means. My bad.
missing() returns TRUE if an argument is not specified in the call _whether
or not_ it has a default, hence the behaviour of missing(y) in debug(plot).
But we can easily find out whether a default has been assigned:
plot(1:10, y=, type=)
Browse[2]> y
NULL
Browse[2]> type
"p"
... which is consistent with silent omission of 'y=' and 'type='
Still waiting for a guru...
Steve E
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