binary form of is() contradicts its unary form
Hi Mehmet,
On 11/29/2017 11:22 AM, Suzen, Mehmet wrote:
Hi Herve, I think you are confusing subclasses and classes. There is no contradiction. `is` documentation is very clear: `With one argument, returns all the super-classes of this object's class.`
Yes that's indeed very clear. So if "list" is a super-class
of "data.frame" (as reported by is(data.frame())), then
is(data.frame(), "list") should be TRUE.
With S4 classes:
setClass("A")
setClass("B", contains="A")
## Get all the super-classes of B.
is(new("B"))
# [1] "B" "A"
## Does a B object inherit from A?
is(new("B"), "A")
# [1] TRUE
Cheers,
H.
Note that object class is always `data.frame` here, check:
> class(data.frame())
[1] "data.frame"
> is(data.frame(), "data.frame")
[1] TRUE
Best,
Mehmet
On 29 Nov 2017 19:13, "Herv? Pag?s" <hpages at fredhutch.org
<mailto:hpages at fredhutch.org>> wrote:
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.
--
Herv? Pag?s
Program in Computational Biology
Division of Public Health Sciences
Fred Hutchinson Canc
<https://urldefense.proofpoint.com/v2/url?u=https-3A__maps.google.com_-3Fq-3DFred-2BHutchinson-2BCanc-26entry-3Dgmail-26source-3Dg&d=DwMFaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=AptypGUf1qnpkFcOc1eU_vdGSHsush3RGVUyjk7yDu8&s=sTr3VPPxYCZLOtlBS3DToP4-Wi44EOLs99gJcV932b0&e=>er
Research Center
1100 Fairview Ave. N, M1-B514
P.O. Box 19024
Seattle, WA 98109-1024
E-mail: hpages at fredhutch.org <mailto:hpages at fredhutch.org>
Phone: (206) 667-5791
Fax: (206) 667-1319
______________________________________________
R-devel at r-project.org <mailto:R-devel at r-project.org> mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
<https://urldefense.proofpoint.com/v2/url?u=https-3A__stat.ethz.ch_mailman_listinfo_r-2Ddevel&d=DwMFaQ&c=eRAMFD45gAfqt84VtBcfhQ&r=BK7q3XeAvimeWdGbWY_wJYbW0WYiZvSXAJJKaaPhzWA&m=AptypGUf1qnpkFcOc1eU_vdGSHsush3RGVUyjk7yDu8&s=OzNPwqjAWVsXOGKMCmd4Fa7Udcm21ewfJmUN78LenQY&e=>
Herv? Pag?s 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: hpages at fredhutch.org Phone: (206) 667-5791 Fax: (206) 667-1319