Re: [R] How can I write methods for 'as()'?
Since nobody else has respond, I thought I'd take a stab. Maybe if I'm
wrong enough somebody will correct me, but my understanding is that that
kind of situation, ie the pain of getting the correct method called when
there is a dependency on the type of more than one argument is part of the
motivation behind the S4 classes. So maybe it really just is that kludgy
for s3 classes.
Jamie Olson
School of Computer Science
Carnegie Mellon University
5000 Forbes Ave.
Pittsburgh, PA 15213
jfol...@cs.cmu.edu
On Mon, Jun 6, 2011 at 12:19 PM, Janko Thyson
janko.thyson.rst...@googlemail.com wrote:
Okay, I found something that is working, but it looks and feels pretty
awkward as the method def and method lookup takes place in one function ;-)
setRefClass(A, fields=list(X=numeric))
setRefClass(B, contains=A, fields=list(Y=character))
mySetAs - function(
from,
to
){
if(!existsMethod(f=coerce, signature=c(from=class(from), to=to))){
setAs(from=class(from), to=to,
def=function(from, to){
out - getRefClass(to)$new(X=from)
return(out)
}
)
}
mthd - selectMethod(coerce, signature=c(from=class(from),
to=to), useInherited= c(from=TRUE, to=TRUE))
out - mthd(from=from, to=to)
return(out)
}
a - mySetAs(from=1:5, to=A)
a$X
b - mySetAs(from=1:5, to=B)
b$X
I'm sure there are much better ways. I'd appreciate any comments
whatsoever.
Best regards,
Janko
On 06.06.2011 17:46, Janko Thyson wrote:
Somehow I don't see my own postings in the list, so sorry for replying
to my own message and not the one that went out to the list.
I got a little further and I think I found exactly the thing that is
bothering me: how to get extended method dispatch going in 'setAs()':
setRefClass(A, fields=list(X=numeric))
setRefClass(B, contains=A, fields=list(Y=character))
setAs(from=numeric, to=A,
def=function(from,to){
out - getRefClass(to)$new(X=from)
return(out)
}
)
a - as(1:5, A)
a$X
b - as(1:5, B)
My problem is the last statement (b - as(1:5, B) which fails. I
want to get around having to write new 'setAs' methods for all classes
extending class 'A'. If 'B' inherits from 'A', shouldn't it then be
possible to tell 'setAs' to look for the next suitable method, i.e.
the method defined for 'A'? I tried 'NextMethod()' inside the body of
'setAs' but that didn't work out.
Thanks a lot,
Janko
On 06.06.2011 17:15, Janko Thyson wrote:
Dear list,
I wonder how to write methods for the function 'as' in the sense that
I can call 'as(object, Class, strict=TRUE, ext)' and let method
dispatch figure out the correct method.
AFAIU, there is a difference between, e.g. 'as.data.frame' and the
methods of 'as()' as stated above since the former depends on arg 'x'
instead of 'object', 'Class' etc.?
methods(as)
as.data.frame
I have to admit that I'm not really familiar with the S3 style of
defining methods as I have been coding in S4 a lot, but my first
attempt was to write something like this:
as.myClass - function(x, ...){
if(is(x, data.frame){
x - as.list(x)
}
if(is(x, character){
x - as.list(x)
}
...
out - getRefClass(myClass)$new(X=x)
return(out)
}
But that way I'd have to explicitly call 'as.myClass(x)' whereas I'd
simply like to type 'as(x, myClass)'.
Also, how is it possible to have method dispatch recognize two
signature arguments in S3? I.e., how can I define something like
'as.data.frame.character' in order to have explicit sub methods for
all the data types of 'x' so I wouldn't have to process them all in
the definition of 'as.myClass' as I did above?
Thanks for your help,
Janko
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
[R] How can I write methods for 'as()'?
Dear list,
I wonder how to write methods for the function 'as' in the sense that I
can call 'as(object, Class, strict=TRUE, ext)' and let method dispatch
figure out the correct method.
AFAIU, there is a difference between, e.g. 'as.data.frame' and the
methods of 'as()' as stated above since the former depends on arg 'x'
instead of 'object', 'Class' etc.?
methods(as)
as.data.frame
I have to admit that I'm not really familiar with the S3 style of
defining methods as I have been coding in S4 a lot, but my first attempt
was to write something like this:
as.myClass - function(x, ...){
if(is(x, data.frame){
x - as.list(x)
}
if(is(x, character){
x - as.list(x)
}
...
out - getRefClass(myClass)$new(X=x)
return(out)
}
But that way I'd have to explicitly call 'as.myClass(x)' whereas I'd
simply like to type 'as(x, myClass)'.
Also, how is it possible to have method dispatch recognize two
signature arguments in S3? I.e., how can I define something like
'as.data.frame.character' in order to have explicit sub methods for
all the data types of 'x' so I wouldn't have to process them all in the
definition of 'as.myClass' as I did above?
Thanks for your help,
Janko
--
*Janko Thyson*
janko.thy...@googlemail.com mailto:janko.thy...@googlemail.com
Jesuitenstraße 3
D-85049 Ingolstadt
Mobile: +49 (0)176 83294257
This e-mail and any attachment is for authorized use by the intended
recipient(s) only. It may contain proprietary material, confidential
information and/or be subject to legal privilege. It should not be
copied, disclosed to, retained or used by any other party.
If you are not an intended recipient then please promptly delete this
e-mail and any attachment and all copies and inform the sender.
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] How can I write methods for 'as()'?
Somehow I don't see my own postings in the list, so sorry for replying
to my own message and not the one that went out to the list.
I got a little further and I think I found exactly the thing that is
bothering me: how to get extended method dispatch going in 'setAs()':
setRefClass(A, fields=list(X=numeric))
setRefClass(B, contains=A, fields=list(Y=character))
setAs(from=numeric, to=A,
def=function(from,to){
out - getRefClass(to)$new(X=from)
return(out)
}
)
a - as(1:5, A)
a$X
b - as(1:5, B)
My problem is the last statement (b - as(1:5, B) which fails. I want
to get around having to write new 'setAs' methods for all classes
extending class 'A'. If 'B' inherits from 'A', shouldn't it then be
possible to tell 'setAs' to look for the next suitable method, i.e. the
method defined for 'A'? I tried 'NextMethod()' inside the body of
'setAs' but that didn't work out.
Thanks a lot,
Janko
On 06.06.2011 17:15, Janko Thyson wrote:
Dear list,
I wonder how to write methods for the function 'as' in the sense that
I can call 'as(object, Class, strict=TRUE, ext)' and let method
dispatch figure out the correct method.
AFAIU, there is a difference between, e.g. 'as.data.frame' and the
methods of 'as()' as stated above since the former depends on arg 'x'
instead of 'object', 'Class' etc.?
methods(as)
as.data.frame
I have to admit that I'm not really familiar with the S3 style of
defining methods as I have been coding in S4 a lot, but my first
attempt was to write something like this:
as.myClass - function(x, ...){
if(is(x, data.frame){
x - as.list(x)
}
if(is(x, character){
x - as.list(x)
}
...
out - getRefClass(myClass)$new(X=x)
return(out)
}
But that way I'd have to explicitly call 'as.myClass(x)' whereas I'd
simply like to type 'as(x, myClass)'.
Also, how is it possible to have method dispatch recognize two
signature arguments in S3? I.e., how can I define something like
'as.data.frame.character' in order to have explicit sub methods for
all the data types of 'x' so I wouldn't have to process them all in
the definition of 'as.myClass' as I did above?
Thanks for your help,
Janko
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] How can I write methods for 'as()'?
Okay, I found something that is working, but it looks and feels pretty
awkward as the method def and method lookup takes place in one function ;-)
setRefClass(A, fields=list(X=numeric))
setRefClass(B, contains=A, fields=list(Y=character))
mySetAs - function(
from,
to
){
if(!existsMethod(f=coerce, signature=c(from=class(from), to=to))){
setAs(from=class(from), to=to,
def=function(from, to){
out - getRefClass(to)$new(X=from)
return(out)
}
)
}
mthd - selectMethod(coerce, signature=c(from=class(from),
to=to), useInherited= c(from=TRUE, to=TRUE))
out - mthd(from=from, to=to)
return(out)
}
a - mySetAs(from=1:5, to=A)
a$X
b - mySetAs(from=1:5, to=B)
b$X
I'm sure there are much better ways. I'd appreciate any comments whatsoever.
Best regards,
Janko
On 06.06.2011 17:46, Janko Thyson wrote:
Somehow I don't see my own postings in the list, so sorry for replying
to my own message and not the one that went out to the list.
I got a little further and I think I found exactly the thing that is
bothering me: how to get extended method dispatch going in 'setAs()':
setRefClass(A, fields=list(X=numeric))
setRefClass(B, contains=A, fields=list(Y=character))
setAs(from=numeric, to=A,
def=function(from,to){
out - getRefClass(to)$new(X=from)
return(out)
}
)
a - as(1:5, A)
a$X
b - as(1:5, B)
My problem is the last statement (b - as(1:5, B) which fails. I
want to get around having to write new 'setAs' methods for all classes
extending class 'A'. If 'B' inherits from 'A', shouldn't it then be
possible to tell 'setAs' to look for the next suitable method, i.e.
the method defined for 'A'? I tried 'NextMethod()' inside the body of
'setAs' but that didn't work out.
Thanks a lot,
Janko
On 06.06.2011 17:15, Janko Thyson wrote:
Dear list,
I wonder how to write methods for the function 'as' in the sense that
I can call 'as(object, Class, strict=TRUE, ext)' and let method
dispatch figure out the correct method.
AFAIU, there is a difference between, e.g. 'as.data.frame' and the
methods of 'as()' as stated above since the former depends on arg 'x'
instead of 'object', 'Class' etc.?
methods(as)
as.data.frame
I have to admit that I'm not really familiar with the S3 style of
defining methods as I have been coding in S4 a lot, but my first
attempt was to write something like this:
as.myClass - function(x, ...){
if(is(x, data.frame){
x - as.list(x)
}
if(is(x, character){
x - as.list(x)
}
...
out - getRefClass(myClass)$new(X=x)
return(out)
}
But that way I'd have to explicitly call 'as.myClass(x)' whereas I'd
simply like to type 'as(x, myClass)'.
Also, how is it possible to have method dispatch recognize two
signature arguments in S3? I.e., how can I define something like
'as.data.frame.character' in order to have explicit sub methods for
all the data types of 'x' so I wouldn't have to process them all in
the definition of 'as.myClass' as I did above?
Thanks for your help,
Janko
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
