[R] find index in a list of list

[Jeff Newmiller]

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-----
>From: "ce" [zadig_1 at excite.com]
>Date: 03/11/2017 10:13 AM
>To: r-help at r-project.org, "Rui Barradas" <ruipbarradas at sapo.pt>
>Subject: Re: [R] find index in a list of list
>
>
>Exactly. Thanks a lot, I was trying sapply with to result. 
>
>-----Original Message-----
>From: "Rui Barradas" [ruipbarradas at sapo.pt]
>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,
>
>Rui Barradas
>
>
>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
>>
>> Thanks in advance
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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 -- To UNSUBSCRIBE and more, see
>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 -- To UNSUBSCRIBE and more, see
>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.