[R] Recursive indexing failed at level 2

[Duncan Murdoch]

On 26/06/2010 8:29 AM, Jim Hargreaves wrote:
> On 06/26/2010 01:20 PM, Duncan Murdoch wrote:
>   
>> On 26/06/2010 7:53 AM, Jim Hargreaves wrote:
>>     
>>> Dear fellow R users,
>>>
>>> I am replacing elements of a list like so:
>>>
>>> pulse_subset[[1:20]]=unlist(pulse[i])[1:20]
>>>       
>> If pulse is a list, then pulse[i] is also a list, with one element.  I 
>> think you want pulse[[i]], which extracts element i.
>>     
> Ahh, I specified pulse[i] has >20 values in my original mail. 
But that could not be correct.  Take a look at length(pulse[i]).  
Assuming that i is a scalar value, length(pulse[i]) will be 1.  You 
really do want pulse[[i]].   You used unlist(pulse[i]) which is 
sometimes the same as pulse[[i]], but it really depends on what 
pulse[[i]] is.  unlist() is a very crude tool, and you should avoid it 
unless you really need it.


> Basically 
> pulse is a list 1000 elements long, with each element in pulse having 
> between 1000 and 2000 elements of it's own. Pulse is a list of lists. 
>   
> Also as far as I am aware, [[ ]]'s should only be used when assigning 
> values to elements of a list/vector.
>   

Whoever told you that was mistaken.

Duncan Murdoch
> unlist(pulse[1]) gives x1, x2, x3, x4, x5 etc. etc.
>   
>> If pulse_subset is a list, then pulse_subset[[1:20]] is equivalent to 
>> pulse_subset[[1]][[2]][[3]][[4]] ... [[20]], i.e. the syntax implies 
>> that it is a list containing a list etc, nested 20 levels deep.  The 
>> error message is telling you that it's not.  I'm not sure what your 
>> intention is in this case.
>> Duncan Murdoch
>>     
>>> where pulse is a list of lists, and pulse [i] has >20 values.
>>>
>>> This gives the error "Recursive Indexing failed at level 2". But, 
>>> interestingly this instruction is part of a loop which has gone 
>>> through about 200,000 iterations before giving this error.
>>>
>>> Actual code:
>>>       
>>> pulse_subset[[1:(length(unlist(pulse[i])[as.numeric(peak_start[i]):as.numeric(peak_end[i])]))]] 
>>> <- unlist(pulse[i])[as.numeric(peak_start[i]):as.numeric(peak_end[i])]
>>>
>>> Error in 
>>> pulse_subset[[1:(length(unlist(pulse[i])[as.numeric(peak_start[i]):as.numeric(peak_end[i])]))]] 
>>> <- unlist(pulse[i])[as.numeric(peak_start[i]):as.numeric(peak_end[i])] :
>>>    recursive indexing failed at level 2
>>>
>>> If anyone could shed some light I'd be rather grateful.
>>>
>>> Regards,
>>> Jim Hargreaves
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> PLEASE do read the posting guide 
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>       
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>