Hi,
The unary forms of is() and extends() report that data.frame
extends list, oldClass, and vector:
> is(data.frame())
[1] "data.frame" "list" "oldClass" "vector"
> extends("data.frame")
[1] "data.frame" "list" "oldClass" "vector"
However, the binary form of is() disagrees:
> is(data.frame(), "list")
[1] FALSE
> is(data.frame(), "oldClass")
[1] FALSE
> is(data.frame(), "vector")
[1] FALSE
while the binary form of extends() agrees:
> extends("data.frame", "list")
[1] TRUE
> extends("data.frame", "oldClass")
[1] TRUE
> extends("data.frame", "vector")
[1] TRUE
Who is right?
Shouldn't 'is(object, class2)' be equivalent
to 'class2 %in% is(object)'? Furthermore, is there
any reason why 'is(object, class2)' is not implemented
as 'class2 %in% is(object)'?
Thanks,
H.
--
Hervé Pagès
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Cancer Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024
E-mail: hpa...@fredhutch.org
Phone: (206) 667-5791
Fax: (206) 667-1319
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
