[R] get element of list with default?

[Spencer Graves]

Thanks to Marc Schwartz and Hadley Wickham:


       Based on their comments, I think I'll add a combination of 
Hadley's code and getElement{base} Ecfun in a form like 
getElement2(object, name, default).


       Best Wishes,
       Spencer


On 4/15/2014 9:33 AM, Hadley Wickham wrote:
> You really want to use the names of the list since lists can contain
> null.  I'd recommend something more like:
>
> getElement <- function(x, i, default) {
>    if (i %in% names(x)) return(x[[i]])
>    default
> }
>
> Hadley
>
> On Tue, Apr 15, 2014 at 10:53 AM, Spencer Graves
> <spencer.graves at structuremonitoring.com> wrote:
>> Hello:
>>
>>
>>        Do you know of a simple function to return the value of a named
>> element of a list if that exists, and return a default value otherwise?
>>
>>
>>        It's an easy function to write (e.g., below).  I plan to add this to
>> the "Ecfun" package unless I find it in another CRAN package.
>>
>>
>>        Thanks,
>>        Spencer
>>
>>
>>      getElement <- function(element, default, list){
>> #       get element of list;  return elDefault if absent
>>          El <- list[[element]]
>>          if(is.null(El)){
>>              El <- default
>>          }
>>          El
>>      }
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>
>


-- 
Spencer Graves, PE, PhD
President and Chief Technology Officer
Structure Inspection and Monitoring, Inc.
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