[R] Normalizing grouped data in a data frame

[Peter Dalgaard]

Greg Snow wrote:
> Here is another approach using transform and ave which I think is a
> little simpler than the others suggested:
>
>   
>> new.data <- transform( iris, 
>>     
> +   normSW = Sepal.Width / ave(Sepal.Width, Species, FUN=max),
> +   normSL = Sepal.Length / ave(Sepal.Length, Species, FUN=max)
> +  )
>
> You can adjust it for your data.  Hope this helps,
>
>   
Yes, I was about to suggest the same. Or

...ave(Sepal.Width, Species, FUN = function(x) x/max(x))..

Should we have a competition for a more evocative name than "ave"?

-- 
   O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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