[R] Recursive indexing failed at level 2

[Duncan Murdoch]

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.

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
>
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