[R] "unfurling" rankings into a matrix of preferences

[Dimitri Liakhovitski]

Yes, correct, thank you, Bert!

On Mon, Jul 27, 2015 at 5:46 PM, Bert Gunter <bgunter.4567 at gmail.com> wrote:
> No it wouldn't.
>
> Presumably you have a typo and meant
>
> rk <- c(2,4,3,1,NA)
>
> ## and set the (5,5) entry to 0 after
>
> -- Bert
>
>
> Bert Gunter
>
> "Data is not information. Information is not knowledge. And knowledge
> is certainly not wisdom."
>    -- Clifford Stoll
>
>
> On Mon, Jul 27, 2015 at 2:32 PM, Dimitri Liakhovitski
> <dimitri.liakhovitski at gmail.com> wrote:
>> With NAs it'd be:
>>
>> rk <- c(2,NA,4,3,1, NA)
>> outer(rk, rk, "<") + 0
>>
>> Wow, I still can't believe it - just one line!
>>
>>
>> On Mon, Jul 27, 2015 at 5:31 PM, Dimitri Liakhovitski
>> <dimitri.liakhovitski at gmail.com> wrote:
>>> Wow!
>>>
>>> On Mon, Jul 27, 2015 at 5:28 PM, Bert Gunter <bgunter.4567 at gmail.com> wrote:
>>>> ## I leave it to you to add the NA edges
>>>>
>>>>> rk <- c(2,4,3,1)
>>>>
>>>>> outer(rk,rk,"<")+0
>>>>
>>>>      [,1] [,2] [,3] [,4]
>>>> [1,]    0    1    1    0
>>>> [2,]    0    0    0    0
>>>> [3,]    0    1    0    0
>>>> [4,]    1    1    1    0
>>>>
>>>>
>>>>
>>>> Cheers,
>>>> Bert
>>>>
>>>> Bert Gunter
>>>>
>>>> "Data is not information. Information is not knowledge. And knowledge
>>>> is certainly not wisdom."
>>>>    -- Clifford Stoll
>>>>
>>>>
>>>> On Mon, Jul 27, 2015 at 12:38 PM, Dimitri Liakhovitski
>>>> <dimitri.liakhovitski at gmail.com> wrote:
>>>>> I have 5 items in total (1:5), but I show a person only 4 items (1:4)
>>>>> and ask this person to rank items 1:4 in terms of preferences (1 is
>>>>> best, 2 is second best, 4 is worst), and I get a vector of ranks:
>>>>> ranks <- c(2,4,3,1)
>>>>>
>>>>> # That means that this person liked item 4 best and item 2 worst.
>>>>>
>>>>> I would like to "unfirl" this vector of ranks into a matrix of
>>>>> preferences where if the row item prefers the column item, then it's a
>>>>> 1. Otherwise, it's a zero. So, the output should be a 5 by 5 matrix
>>>>> (because overall we have 5 items, not 4, but item 5 did not
>>>>> participate in rankings), and it would always have zeros in a
>>>>> diagonal.:
>>>>>
>>>>> 0    1    1    0 NA
>>>>> 0    0    0    0 NA
>>>>> 0    1    0    0 NA
>>>>> 1    1    1    0 NA
>>>>> NA NA NA NA 0
>>>>>
>>>>> I can loop through all possible pairs the person saw and fill the
>>>>> matrix accordingly, but it seems like a lot of looping. Could one do
>>>>> it in a more elegant way?
>>>>>
>>>>> Thank you very much!
>>>>>
>>>>>
>>>>> --
>>>>> Dimitri Liakhovitski
>>>>>
>>>>> ______________________________________________
>>>>> 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.
>>>
>>>
>>>
>>> --
>>> Dimitri Liakhovitski
>>
>>
>>
>> --
>> Dimitri Liakhovitski



-- 
Dimitri Liakhovitski