[R] Recursive Indexing Failed

[peter dalgaard]

On May 9, 2011, at 15:24 , Alaios wrote:

> So the only thing that might work is a for..loop to collect all these together?

An implicit loop using lapply/sapply might be more like it:

lapply(CRagentInTime[[1]]$CRagent[1:10], "[[", "sr")

Notice that fancy indexing usually requires "[", not "[[".

> 
> Best REgards
> Alex
> 
> --- On Mon, 5/9/11, Patrick Breheny <patrick.breheny at uky.edu> wrote:
> 
>> From: Patrick Breheny <patrick.breheny at uky.edu>
>> Subject: Re: [R] Recursive Indexing Failed
>> To: "Alaios" <alaios at yahoo.com>
>> Cc: "R-help at r-project.org" <R-help at r-project.org>
>> Date: Monday, May 9, 2011, 2:18 PM
>> On 05/09/2011 08:58 AM, Alaios
>> wrote:
>>> Dear all,
>>> I would like to ask your help concerning an error
>> message I get.
>>> 
>>> I have the following struct
>>> 
>>> str(CRagentInTime[[1]])
>>> List of 2
>>>    $ timelag: int 0
>>>    $ CRagent:List of 50
>>>     ..$ :List of 3
>>>     .. ..$ CRmap: num [1:256, 1:256] NA NA NA
>> NA NA NA NA NA NA NA ...
>>>     .. ..$ xy   : num [1:2] 10
>> 177
>>>     .. ..$ sr   : num [1:49]
>> -94.9 -92.8 -79.5 -97.6 -78.4 ...
>>> 
>>> and I wanted to select all the sr fields for every of
>> each one of the 50 CRagent Lists I have.
>>> 
>>> So I tried something like
>>> 
>>> str(CRagentInTime[[1]][[2]][[1:10]]$sr) and I get a
>> message that
>>> Error in CRagentInTime[[1]][[2]][[1:10]] :
>>>     recursive indexing failed at level 3
>> 
>> Selecting multiple elements of a list using an expression
>> like [[1:10]] 
>> does not work.  For example:
>> 
>> x <- list("a","b")
>> x[[1:2]]
>> 
>> produces
>> 
>> Error in x[[1:2]] : subscript out of bounds
>> 
>> In general, the expression x[[1:2]] is not meaningful, as
>> the elements 
>> of the list may be of different type, with no way to
>> concatenate them.
>> 
>>> 
>>> strange to me is that this one works
>>> 
>>> str(CRagentInTime[[1]][[2]][[1]]$sr)
>>>    num [1:49] -106 -92.9 -101.3 -81.9
>> -96.7 ...
>>> 
>>> 
>>> I would like to thank you in advance for your help
>>> Best Regards
>>> Alex
>>> 
>> _______________________
>> Patrick Breheny
>> Assistant Professor
>> Department of Biostatistics
>> Department of Statistics
>> University of Kentucky
>> 
> 
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-- 
Peter Dalgaard
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com