[R] Simple programming question
Gabor Grothendieck
ggrothendieck at gmail.com
Fri May 18 16:31:38 CEST 2007
There was a problem in the first line in the case that the highest number
is not unique within a category. In this example its not apparent since
that never occurs. At any rate, it should be:
f <- function(x) 4 - pmin(3, match(x, sort(unique(x), decreasing = TRUE)))
factor(ave(dfr$var3, dfr$categ, FUN = f), lab = c("low", "mid", "high"))
Also note that the factor labels were arranged so that
"low", "mid" and "high" correspond to levels 1, 2 and 3
respectively.
On 5/18/07, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> Try this. f assigns 1, 2 and 3 to the highest, second highest and third highest
> within a category. ave applies f to each category. Finally we convert it to a
> factor.
>
> f <- function(x) 4 - pmin(3, match(x, sort(x, decreasing = TRUE)))
> factor(ave(dfr$var3, dfr$categ, FUN = f), lab = c("low", "mid", "high"))
>
>
>
> On 5/18/07, Lauri Nikkinen <lauri.nikkinen at iki.fi> wrote:
> > Hi R-users,
> >
> > I have a simple question for R heavy users. If I have a data frame like this
> >
> >
> > dfr <- data.frame(id=1:16, categ=rep(LETTERS[1:4], 4),
> > var3=c(8,7,6,6,5,4,5,4,3,4,3,2,3,2,1,1))
> > dfr <- dfr[order(dfr$categ),]
> >
> > and I want to score values or points in variable named "var3" following this
> > kind of logic:
> >
> > 1. the highest value of var3 within category (variable named "categ") ->
> > "high"
> > 2. the second highest value -> "mid"
> > 3. lowest value -> "low"
> >
> > This would be the output of this reasoning:
> >
> > dfr$score <-
> > factor(c("high","mid","low","low","high","mid","mid","low","high","mid","low","low","high","mid","low","low"))
> > dfr
> >
> > The question is how I do this programmatically in R (i.e. if I have 2000
> > rows in my dfr)?
> >
> > I appreciate your help!
> >
> > Cheers,
> > Lauri
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > 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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