For the record, Henrique's use of rowsum() is about 10 times faster
than using tapply (and presumably anything with table() ) on my
computer. It call a C primitive.
-- Bert
On Wed, Aug 31, 2011 at 9:55 AM, Henrique Dallazuanna <www...@gmail.com> wrote:
> Try this:
>
> rowsum(x, y)
>
> On Wed, Aug 31, 2011 at 1:45 PM, zhenjiang xu <zhenjiang...@gmail.com> wrote:
>>
>> Hi R users,
>>
>> suppose I have two vectors,
>> > x=c(1,2,3,4,5)
>> > y=c('a','b','c','a','c')
>> How can I get a data.frame like this?
>> > xy
>> count
>> a 5
>> b 2
>> c 8
>>
>> I know a few ways to fulfill the task. However, I have a huge number
>> of this kind calculations, so I'd like an efficient solution. Thanks
>>
>> --
>> Best,
>> Zhenjiang
>>
>> ______________________________________________
>> R-help@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-Paraná-Brasil
> 25° 25' 40" S 49° 16' 22" O
>
> ______________________________________________
> R-help@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.
>
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