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

Bert Gunter bgunter.4567 at gmail.com
Mon Jul 27 23:46:26 CEST 2015


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



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