[R] a more elegant way to get percentages?

[(Ted Harding)]

Now that people have answered Monica's query, can someone help me?!!
See below.

On 13-Mar-08 13:36:03, Monica Pisica wrote:
> 
> Hi,
> 
> I am trying to get percentages in a more elegant way. I have a
> data.frame with locations and values (counts) of species at that
> location. Each location is repeated for each species i have values for
> and i would like to get percentages of each species at that location. I
> am not sure if i am clear in my explanations so i will paste my code
> below:
> 
>#####################
> 
>> x
>    locat val
> 1      a   5
> 2      b   5
> 3      b  15
> 4      c   5
> 5      c  20
> 6      c   5
> 7      c  10
> 8      d   5
> 9      d  15
> 10     d  10

With Monica's dataframe as above, the answer would be 100*x[,1]/z
where we want z to be c(5,20,20,40,40,40,40,30,30,30).

So, intending to give Monica a helpful answer, I tried

> apply(x,1,function(y) sum(x[x[,1]==y,2]))
 1  2  3  4  5  6  7  8  9 10 
 5 15 15 30 30 30 30 15 15 15 

and similarly

> apply(x,1,function(y) sum(x$val[x$locat==y]))
 1  2  3  4  5  6  7  8  9 10 
 5 15 15 30 30 30 30 15 15 15


So why didn't this work? Where's my blind spot? Indeed, why
did it gives the results it did?

With thanks,
Ted.

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Date: 13-Mar-08                                       Time: 14:15:34
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