[R] cast in reshape and reshape2

[David Winsemius]

On Dec 23, 2011, at 2:58 PM, Kaiyin Zhong wrote:

>> library(reshape2)
>> x = melt(airquality, id=c('month', 'day'))
>
> With reshape I can cast with multiple functions:
>
>> library(reshape)
>> cast(x, month+variable~., c(mean,sd))
>   month variable       mean         sd
> 1      5    ozone  23.615385  22.224449
> 2      5  solar.r 181.296296 115.075499
> 3      5     wind  11.622581   3.531450
> 4      5     temp  65.548387   6.854870
> 5      6    ozone  29.444444  18.207904
> 6      6  solar.r 190.166667  92.882975
> 7      6     wind  10.266667   3.769234
> 8      6     temp  79.100000   6.598589
> 9      7    ozone  59.115385  31.635837
> 10     7  solar.r 216.483871  80.568344
> 11     7     wind   8.941935   3.035981
> 12     7     temp  83.903226   4.315513
> 13     8    ozone  59.961538  39.681210
> 14     8  solar.r 171.857143  76.834943
> 15     8     wind   8.793548   3.225930
> 16     8     temp  83.967742   6.585256
> 17     9    ozone  31.448276  24.141822
> 18     9  solar.r 167.433333  79.118280
> 19     9     wind  10.180000   3.461254
> 20     9     temp  76.900000   8.355671
>
> Is there a way to do the same job with reshape2?

Have you looked at the .summarise argument to dcast? That seems to  
deliver the same sort of results one gets with base::aggregate.

-- 
David Winsemius, MD
West Hartford, CT