Dear Srini,
Here is one way:

# Data set
x=read.table(textConnection("fruit weight
1  apple    1.3
2  apple    1.5
3  apple    1.6
4 orange    1.4
5 orange    1.6"),header=TRUE)

x[tapply(x$weight,x$fruit,which.max),]
 apple orange
   1.6    1.6

or


Try also

x[cumsum(tapply(x$weight,x$fruit,which.max)),]
fruit weight
3  apple    1.6
5 orange    1.6


HTH,

Jorge



On Sun, Sep 7, 2008 at 10:24 PM, Srinivas Iyyer
<srini_iyyer_bio@yahoo.com>wrote:

> dear group,
> i have a data matrix with some replicate items with different values. I
> want to extract the row with max value.
>
> for example:
> > x
>   fruit weight
> 1  apple    1.3
> 2  apple    1.5
> 3  apple    1.6
> 4 orange    1.4
> 5 orange    1.6
>
>
> x is a data frame.
> I want to extract unique items from fruits that has max weight.
>
> that is:
>
> 3  apple    1.6
> 5 orange    1.6
>
> I want to be able to use apply functions. Could some one lend some help
> please.
>
> Thanks
> srini
>
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