[R] using data.table ,plyr

[Hadley Wickham]

It's rude to ask a question both on r-help and on stackoverflow
(http://stackoverflow.com/questions/22685896), because people might
spend their time answering your question when it's already been
answered elsewhere.

Hadley

On Thu, Mar 27, 2014 at 6:01 AM, Rohit Gupta <rhtgpt789 at gmail.com> wrote:
> I have a data A which looks like
>
>
>     author_id paper_id prob
>        731    24943    1
>        731    24943    1
>        731 688974 1
>        731   964345    .8
>        731  1201905    .9
>        731  1267992    1
>        736    249      .2
>        736   6889      1
>        736   94345    .7
>        736  1201905    .9
>        736  126992    .8
>
> The output I am desiring is:
>
>     author_id    paper_id
>       731        24943,24943,688974,1201905,964345
>       736        6889,1201945,126992,94345,249
>
> That is paper_id are arranged according to decreasing order of
> probability.How could this be done?
>
> Thanks
>
>         [[alternative HTML version deleted]]
>
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