Thank you both for response!
Enh, I never think about function though. Good.
My way is using 'aggregate' and 'merge' but it is a little bit trivial.
On Wed, Aug 11, 2010 at 9:13 PM, Dennis Murphy <djmu...@gmail.com> wrote:
> Hi:
>
> Try this from package plyr:
>
> library(plyr)
> # function to compute sum of squares
> f <- function(df) with(df, sum((tapply(value, type, sum)/sum(value))^2))
> # apply it to each type of food:
> ddply(data, .(food), conc = f(data))
> food type value market_con
> 1 drink water 5 0.5987654
> 2 drink soda 7 0.5987654
> 3 drink soda 6 0.5987654
> 4 fruit apple 2 0.7222222
> 5 fruit apple 3 0.7222222
> 6 fruit orange 1 0.7222222
>
> HTH,
> Dennis
>
> On Wed, Aug 11, 2010 at 3:40 PM, Yi <liuyi.fe...@gmail.com> wrote:
>
>> Thank you for reminding me.
>>
>> ######
>> food=c('fruit','fruit','fruit','drink','drink','drink')
>> type=c('apple','apple','orange','water','soda','soda')
>> value=c(2,3,1,5,7,6)
>> data=data.frame(food,type,value)
>> share=c((2+3)/(2+3+1),5/6,1/6,5/(5+7+6),13/18,13/18)
>>
>> market_con=c(rep(0.8333333^2+0.1666667^2,3),rep(0.2777778^2+0.7222222^2,3))
>> data$market_con=market_con
>> ######
>>
>> Share= sum of value for specific type for some food / sum of value for all
>> types for some food
>>
>> concentration= sum of square of share
>>
>> For food 1, fruit, for apple ,there are two rows, value =2 and 3; for
>> oranget, value =1.
>>
>> share_apple=(2+3)/(2+3+1)=5/6 ## It is the same for the two rows
>> share_organge=1/6
>>
>> concentration_fruit= share_apple^2+sjare_orange^2=(5/6)^2+(1/6)^2
>>
>> Hope this makes it easier to understand.
>>
>> Thanks
>>
>> Yi
>>
>> On Wed, Aug 11, 2010 at 3:33 PM, Wu Gong <w...@mtmail.mtsu.edu> wrote:
>>
>> >
>> > Hi Yi,
>> >
>> > It would be helpful for others to provide a solution if you give your
>> > formulas that calculating the value of share and concentration.
>> >
>> > ?apply will helps.
>> >
>> > Regards,
>> >
>> > Wu
>> >
>> >
>> >
>> > -----
>> > A R learner.
>> > --
>> > View this message in context:
>> >
>> http://r.789695.n4.nabble.com/How-to-calculate-the-concentration-tp2321888p2321966.html
>> > Sent from the R help mailing list archive at Nabble.com.
>> >
>> > ______________________________________________
>> > 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<http://www.r-project.org/posting-guide.html>
>> <http://www.r-project.org/posting-guide.html>
>>
>> > and provide commented, minimal, self-contained, reproducible code.
>> >
>>
>> [[alternative HTML version deleted]]
>>
>>
>> ______________________________________________
>> 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<http://www.r-project.org/posting-guide.html>
>> and provide commented, minimal, self-contained, reproducible code.
>>
>
>
[[alternative HTML version deleted]]
______________________________________________
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.
