On 10/22/2008 10:02 AM, francois Guilhaumon wrote:
Hello,
I'm looking for a way to get the "name" of an object when it is used
within an "sapply".
More precisely, with a simple example :
I have a named list of objects :
myList = list(a=rnorm(10),b=rnorm(10),c=rnorm(10))
I would like to create a new object from each of the components of
myList using the "sapply" function, for example to get the mean of all
components of myList :
createVarMean = function(obj){
obj.name = ******
obj.mean = mean(obj)
assign(obj.name,obj.mean)
}#end of createVarMean
sapply doesn't pass the names in, but there are other choices:
sapply(seq_along(myList), function(i) list(obj.name=names(myList)[i],
obj.mean = mean(myList[[i]])))
which iterates over the indices of myList, rather than over the elements
of it. But a simple sapply(myList, function(obj) mean(obj)) is probably
preferable, since it attaches the names in a nice way:
> sapply(myList, function(obj) mean(obj))
a b c
-0.4097454 -0.5057526 -0.2204035
Using :
sapply(myList,createVarMean)
Should then create all the objects.
Any idea to get the names ? Perhaps using object oriented programming
(is there an equivalent of the "this" syntax of Java in R ?) ?
Object oriented stuff in R is quite different from Java, because R
doesn't have pointers or references except in very special cases.
Duncan Murdoch
I don't want to use a loop here.
thank you for your time and trouble,
François.
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