On Jan 30, 2009, at 10:30 , Christian Brechbühler wrote:
On Thu, Jan 29, 2009 at 4:44 PM, Prof Brian Ripley <rip...@stats.ox.ac.uk
>wrote:
What did your actual application do? This seems a very strange
thing to
do, and the segfault is in trying to construct the traceback.
Only by using do.call on the object (and not even by name) do I get
this
error. E.g.
`[.data.frame`(1:10, 3)
Error in NextMethod("[") : object not specified
do.call("[.data.frame", list(1:10, 3))
Error in NextMethod("[") : object not specified
are fine.
Obviously it would be nice to fix this, but I'd like to understand
the
actual circumstances: there is more to it than the subject line.
Yes, there is more. For reporting the problem, we tried to pare it
down to
a concise, self-contained test case.
My boss was debugging an issue in our R code. We have our own "[...."
functions, because stock R drops names when subscripting.
... if you tell it to do so, yes. If you tell it to not do that, it
won't ... ever tried drop=FALSE ?
Cheers,
S
To bypass our
now-suspect functions and get the "real" subscripting method, he
used "get"
from package:base. He was examining a large object, and believing
it was a
data frame, chose "[.data.frame". As it turns out, that object was
not a
data frame, and he got an unexpected segfault. I think it was a
matrix.
But it doesn't matter -- a vector as in the test case will give the
same.
We have since fixed the bug in our replacement subscripting
function, so the
issue might not affect us any more.
Thanks,
/Christian
On Thu, 29 Jan 2009, brechbueh...@gmail.com wrote:
Full_Name: Christian Brechbuehler
Version: 2.7.2, 2.8.1
OS: linux-gnu
If we mistakenly believe the object is a data frame (as we did in
a much
more
complicated real situation), this happens:
do.call(get("[.data.frame",pos="package:base"),list(1:10,3))
Error in NextMethod("[") :
no calling generic was found: was a method called directly?
*** caught segfault ***
address (nil), cause 'unknown'
Process R:2 segmentation fault (core dumped) at Thu Jan 29
09:26:29 2009
The Error message is appropriate. But the segmentation fault is
unexpected.
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