# [R] is there a way to recursilvely lapply

Whit Armstrong armstrong.whit at gmail.com
Thu Dec 11 23:33:55 CET 2008

```yes, that is correct. I was looking in text mode.

-Whit

On Thu, Dec 11, 2008 at 4:02 PM, Prof Brian Ripley
<ripley at stats.ox.ac.uk> wrote:
> On Thu, 11 Dec 2008, Whit Armstrong wrote:
>
>> Thanks, Gabor and Prof. Ripley.
>>
>> Sorry for the oversight.
>>
>> I grepped the lapply help for recursive prior to sending my question.
>>
>> why does it appear as "*r*ecursive" in the help file? or is that just
>> a formating problem on my machine?
>
> It is marked as bold: I presume you are reading text help?
>
>>
>> -Whit
>>
>>
>> On Thu, Dec 11, 2008 at 3:13 PM, Prof Brian Ripley
>> <ripley at stats.ox.ac.uk> wrote:
>>>
>>> On Thu, 11 Dec 2008, Whit Armstrong wrote:
>>>
>>>> for a simple example:
>>>>
>>>> x <- list()
>>>> x[["a"]] <- list(a=c(1,2,3),b=c(3,4,5))
>>>> x[["b"]] <- list(a=c(6,7,8),b=c(9,10,11))
>>>>
>>>> lapply(x,sum)
>>>>
>>>>
>>>> this fails w/
>>>> Error in FUN(X[[1L]], ...) : invalid 'type' (list) of argument
>>>>
>>>> Just wondering if I have overlooked something obvious.
>>>
>>> rapply?  Which is linked from ?lapply (I just checked).  Perhaps
>>>
>>>> rapply(x, sum)
>>>
>>> a.a a.b b.a b.b
>>>  6  12  21  30
>>>
>>> or
>>>
>>>> rapply(x, sum, how="list")
>>>
>>> \$a
>>> \$a\$a
>>> [1] 6
>>> .....
>>>
>>>>
>>>> one can also do:
>>>>
>>>> lapply(x,lapply,sum)
>>>>
>>>> but that assumes that you already know how many levels you have, and
>>>> that all the levels are consistent.
>>>>
>>>> -Whit
>>>>
>>>> ______________________________________________
>>>> R-help at r-project.org mailing list
>>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>>> http://www.R-project.org/posting-guide.html
>>>> and provide commented, minimal, self-contained, reproducible code.
>>>>
>>>
>>> --
>>> Brian D. Ripley,                  ripley at stats.ox.ac.uk
>>> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
>>> University of Oxford,             Tel:  +44 1865 272861 (self)
>>> 1 South Parks Road,                     +44 1865 272866 (PA)
>>> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>>>
>>
>
> --
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>

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