Hi,When I read the source of str,i find these code
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## Show further classes // Assume that they do NOT have an own Method --
## not quite perfect ! (.Class = 'remaining classes', starting with current)
cl <- oldClass(object); cl <- cl[cl != "data.frame"] #- not THIS class
-----
so I use ?oldClass to try to learn more about oldClass.But after I have reading all the help page ,I still have no idea the diiference between oldClass and class.
Anynone can help me ?
2005-08-06
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Deparment of Sociology
Fudan University
Blog:http://sociology.yculblog.com
oldClass vs. class
2 messages · ronggui, Brian Ripley
On Sat, 6 Aug 2005, ronggui wrote:
Hi,When I read the source of str,i find these code ----- ## Show further classes // Assume that they do NOT have an own Method -- ## not quite perfect ! (.Class = 'remaining classes', starting with current) cl <- oldClass(object); cl <- cl[cl != "data.frame"] #- not THIS class -----
so I use ?oldClass to try to learn more about oldClass.But after I have reading all the help page ,I still have no idea the diiference between oldClass and class.
From the help page
Many R objects have a 'class' attribute, a character vector giving
the names of the classes which the object "inherits" from. If the
object does not have a class attribute, it has an implicit class,
'"matrix"', '"array"' or the result of 'mode(x)'. (Functions
'oldClass' and 'oldClass<-' get and set the attribute, which can
also be done directly.)
so class returns the implicit class, and oldClass does not.
A <- matrix(1:6, 2,3) class(A)
[1] "matrix"
oldClass(A)
NULL just as it says.
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595