[R] create an object in a loop (v3)

[Chris Campbell]

On Tue, Feb 2, 2010 at 11:44, Ivan Calandra
<ivan.calandra at uni-hamburg.de> wrote:
> Hi David,
>
> Thanks for your answer.
> But I don't really see how I can extend it with my real data.
> The thing is that I have more than 3 names and 1 value for each name.
> Moreover, each is different from one run to another. That is why I was
> trying with a modification of names(). Also to be noted is that I simplified
> the "name" in assign(); I actually have 2 other variables that will be
> pasted to create the name.
>
> Here is my code (I kept only what is important for that part):
> ----
> library(WRS)
> seq.num <- seq(7,10,1)        #column (variable) indexes to be used as
> numerical variables
>
> # fac2list() separates the data from file[,k] into groups from levels in
> file[3] and store into list mode.
> for(i in 1:length(seq.num)) {
>  k <- seq.num[i]
>  name.num <- names(file)[k]
>  assign(paste(names(file)[3], name.num, sep="_"), fac2list(file[,k],
> file[3]))
>  names(paste(names(file)[3], name.num, sep="_")) <-
> levels(factor(file[[3]]))  #that line doesn't work, but I would like
> something in this direction
> }
> ----

Sounds like a job for 'get'.  Try this (untested):

names(get(paste(names(file)[3], name.num, sep="_")))

Good luck

>
> Thanks in advance for your help.
> Regards,
> Ivan
>
>
>
> Le 2/1/2010 18:47, David Winsemius a écrit :
>>
>> On Feb 1, 2010, at 12:33 PM, Ivan Calandra wrote:
>>
>>> I have a follow-up question:
>>>
>>> I use assign() to store some value in my paste()-created object as
>>> suggested:
>>> for (i in 1:3) {
>>> assign(paste("object", i, sep=""), c("a", "b", "c"))
>>> }
>>>
>>> Then I would like to change the names of the elements of that object
>>> within the loop. Since it is all in a loop, I cannot give the name of the
>>> object manually by doing something like: names(object1) <- c("tooth",
>>> "bone", "species").
>>> The only thing I can give to names() is paste("object", i, sep=""), which
>>> doesn't work.
>>>
>>> Any idea of how to do it?
>>
>> > for (i in paste("object", 1:3, sep="")) {
>> + assign(i, c("tooth"="a", "bone"="b", "species"="c") )
>> + }
>> > object1
>>  tooth    bone species
>>    "a"     "b"     "c"
>>
>>>
>>> Thanks in advance
>>> Ivan
>>>
>>>
>>> Le 2/1/2010 17:14, David Winsemius a écrit :
>>>>
>>>> Upon reading it yesterday, it appeared as it would have required some
>>>> serious testing and there was no data on which to do any work.  You were
>>>> clearly not taking the time to isolate the problem and construct a dataset.
>>>> But who knows? When you say "What I want to do is. ... ,I would like the
>>>> name of the list to be created in the loop too", maybe all you needed was to
>>>> be pointed to was:
>>>>
>>>> ?assign
>>>>
>>>> But if that were the case, then you lost most of your audience along the
>>>> way with a bunch of unneeded and obscure code.
>>>>
>>
>> David Winsemius, MD
>> Heritage Laboratories
>> West Hartford, CT
>>
>>
>
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