>>>>> "Gregor" == Gregor Gorjanc <[EMAIL PROTECTED]>
>>>>> on Sat, 04 Nov 2006 02:09:13 +0100 writes:
Gregor> Ferdinand Alimadhi wrote:
>> tmp$comp <- [EMAIL PROTECTED] ?!
Gregor> I "lose" class here and that is not what I
Gregor> want. Perhaps I should stick with list instead of
Gregor> data.frame.
Yes, I probably would, at least for the time being.
OTOH, it's interesting that some methods to "stick some S4
objects into a data frame do work fine , at least for the
following case (R-script below) -- and I wonder if we (R developers)
shouldn't think about more explicitly supporting this,
e.g., by stating something like
>> If an S4 object simply *contains* an atomic class that can be
>> used as data.frame column, then that S4 object can also be used
>> as data.frame column
and trying to fix all cases where the above is not fulfilled.
setClass("Real", contains="numeric")
(r <- new("Real", pi * 1:3))
try( dd <- data.frame(x = 1:3, R = r) ) ## fails
## Error in as.data.frame.default(x[[i]], optional = TRUE) :
## cannot coerce class "Real" into a data.frame
dd <- data.frame(x = 1:3)
dd[,"R"] <- r ## works fine .. didn't I say just yesterday how much
## I recommend [, <name>] indexing for data frames ?
dd
str(dd)
dd[1:2,]
## but
str(dd[1:2,]) # has lost the class -- of course since r[1:2] loses it
## -> you need to define a correct subset method for your class
## e.g.,
setMethod("[", signature(x = "Real", i = "ANY"),
function(x, i,j,drop, ...) new("Real", callNextMethod()))
r[1:2] # now correct
str(dd[1:2,]) # correct too
Martin Maechler, ETH Zurich
>> Gregor Gorjanc wrote:
>>
>>> Hello!
>>>
>>> I am developing a composition class, which represents a
>>> composition of mixture of levels, say soil has three
>>> components and each component accounts for 1/3 of the
>>> unit. I have tried with S4 class system and I would
>>> appreciate any help here. I was hoping that I would be
>>> able to include instance of my class into a
>>> data.frame. However, I encounter problems.
>>>
>>> Simple definition of class could be
>>>
>>> setClass(Class="composition",
>>> representation=representation(ratios="matrix"))
>>>
>>> n <- 2 k <- 3
>>>
>>> x <- new(Class="composition",
>>> ratios=matrix(data=rep(x=1/3, times=n*k), nrow=n,
>>> ncol=k))
>>>
>>> x An object of class "composition" Slot "ratios": [,1]
>>> [,2] [,3] [1,] 0.3333333 0.3333333 0.3333333 [2,]
>>> 0.3333333 0.3333333 0.3333333
>>>
>>> tmp <- data.frame(id=1:2) tmp$comp <- x Error: object is
>>> not subsettable
>>>
>>> As I understand this, my problem is that x is of length
>>> 1 as the following works
>>>
>>> tmp$comp <- c(x, x)
>>>
>>> although I am not able to print tmp now
>>>
>>> tmp Error in unlist(x, recursive, use.names) : argument
>>> not a list
>>>
>>> but this is expected as I (probably) need show/print
>>> method for this. How can I put my class into data.frame
>>> or how can I make my class behave as a vector?
>>>
>>> Thanks!
Gregor> -- Lep pozdrav / With regards, Gregor Gorjanc
Gregor>
----------------------------------------------------------------------
Gregor> University of Ljubljana PhD student Biotechnical
Gregor> Faculty Zootechnical Department URI:
Gregor> http://www.bfro.uni-lj.si/MR/ggorjan Groblje 3 mail:
Gregor> gregor.gorjanc <at> bfro.uni-lj.si
Gregor> SI-1230 Domzale tel: +386 (0)1 72 17 861 Slovenia,
Gregor> Europe fax: +386 (0)1 72 17 888
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