R help - May 2011 - Test for list membership

Hi,

I need some help with this one: how do I check whether a vector is
already present in a list of vectors.

I have seen %in% recommended in a similar case but that obviously does
not work here.

c(1,2,3) %in% list(c(1,2,3), c(4,5,6))

returns

[1] FALSE FALSE FALSE

which makes sense since 1, 2 or 3 are not elements of that list. I don't
really know how to move from there though.

Best wishes,
Marcin

Try this:

list(c(1,2,3), c(4,5,6)) %in% list(c(1,2,3))

On Mon, May 30, 2011 at 10:36 AM, Marcin Wlodarczak
<mwlodarczak at uni-bielefeld.de> wrote:
>
> Hi,
>
> I need some help with this one: how do I check whether a vector is
> already present in a list of vectors.
>
> I have seen %in% recommended in a similar case but that obviously does
> not work here.
>
> c(1,2,3) %in% list(c(1,2,3), c(4,5,6))
>
> returns
>
> [1] FALSE FALSE FALSE
>
> which makes sense since 1, 2 or 3 are not elements of that list. I
don't
> really know how to move from there though.
>
> Best wishes,
> Marcin
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>


-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O

On 30.05.2011 15:36, Marcin Wlodarczak wrote:
>
> Hi,
>
> I need some help with this one: how do I check whether a vector is
> already present in a list of vectors.
>
> I have seen %in% recommended in a similar case but that obviously does
> not work here.
>
> c(1,2,3) %in% list(c(1,2,3), c(4,5,6))

You said it yourself, almost:

list(c(1,2,3)) %in% list(c(1,2,3), c(4,5,6))

Uwe Ligges

> returns
>
> [1] FALSE FALSE FALSE
>
> which makes sense since 1, 2 or 3 are not elements of that list. I
don't
> really know how to move from there though.
>
> Best wishes,
> Marcin
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.

You almost solved your own problem with that last statement. Instead
of comparing apples and oranges, you need to compare oranges and
oranges:
> list(c(1,2,3)) %in% list(c(1,2,3), c(4,5,6))
[1] TRUE
> list(c(1,2,3)) %in% list(c(1,2,9), c(4,5,6))
[1] FALSE

Sarah


On Mon, May 30, 2011 at 9:36 AM, Marcin Wlodarczak
<mwlodarczak at uni-bielefeld.de> wrote:
>
> Hi,
>
> I need some help with this one: how do I check whether a vector is
> already present in a list of vectors.
>
> I have seen %in% recommended in a similar case but that obviously does
> not work here.
>
> c(1,2,3) %in% list(c(1,2,3), c(4,5,6))
>
> returns
>
> [1] FALSE FALSE FALSE
>
> which makes sense since 1, 2 or 3 are not elements of that list. I
don't
> really know how to move from there though.
>
> Best wishes,
> Marcin
>
-- 
Sarah Goslee
http://www.functionaldiversity.org

On 05/30/2011 04:14 PM, Uwe Ligges wrote:
> On 30.05.2011 15:36, Marcin Wlodarczak wrote:
>>
>> Hi,
>>
>> I need some help with this one: how do I check whether a vector is
>> already present in a list of vectors.
>>
>> I have seen %in% recommended in a similar case but that obviously does
>> not work here.
>>
>> c(1,2,3) %in% list(c(1,2,3), c(4,5,6))
>
>
> You said it yourself, almost:
>
> list(c(1,2,3)) %in% list(c(1,2,3), c(4,5,6))
Brilliant! Thanks to everyone.

Marcin