[R] find index in a list of list

Jeff Newmiller jdnewmil at dcn.davis.ca.us
Sat Mar 11 17:23:00 CET 2017

```Since the offered solution already checks each top level element using the "identical" function, you just need a different comparison function, like perhaps:

mycompare <- function( x, y ) {
identical( x[[ "a" ]], y[[ "a" ]] ) && identical( x[[ "b" ]], y[[ "b" ]] )
}

Note that your decision to store this data in a list of lists is making this search process much less computationally and syntactically efficient than it would be if you could fit your data into a data frame.
--
Sent from my phone. Please excuse my brevity.

On March 11, 2017 7:17:11 AM PST, ce <zadig_1 at excite.com> wrote:
>
>
>Sorry I rejoiced  too soon. In fact original list is more complex like
>:
>
>mylist <-
>list(list(a=10,b="x",c=1),list(a=11,b="y",c=2),list(a=12,b="z",c=5))
>
>and I still need to find index of where a = 11 and b = "y"  and I have
>no c value ,
>
>-----Original Message-----
>Date: 03/11/2017 10:13 AM
>Subject: Re: [R] find index in a list of list
>
>
>Exactly. Thanks a lot, I was trying sapply with to result.
>
>-----Original Message-----
>Date: 03/11/2017 10:06 AM
>To: "ce" <zadig_1 at excite.com>, r-help at r-project.org
>Subject: Re: [R] find index in a list of list
>
>Hello,
>
>Something like this?
>
>find <- list(a=11,b="y")
>which(sapply(mylist, identical, find))
>
>Hope this helps,
>
>
>
>Em 11-03-2017 14:59, ce escreveu:
>> Hi all,
>>
>> I have a list of lists like this :
>>
>> mylist <- list(list(a=10,b="x"),list(a=11,b="y"),list(a=12,b="z"))
>>
>> I want to find the index of list in mylist where a = 11 and b  = "y"
>, so I want to get 2 as a result
>>
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>______________________________________________
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>and provide commented, minimal, self-contained, reproducible code.
>
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