[R] select duplicate identifier with higher mean across sample columns

[Adrian Johnson]

Hi Group:
I searched R groups before posting this question. I could not find the
appropriate answer and I do not have clear understanding how to do
this in R.

I have a data frame with duplicated row identifiers but with different
values across columns. I want to select the identifier with higher
inter-quartile range or mean.


 id <- c("A", "A", "C", "D", "E", "F")
 year <- c(2000, 2001, 2001, 2002, 2003, 2004)
 samp1 <- c(100, 120, 101, 110, 132,123)
 samp2 <- c(110, 130, 131, 150, 122,143)
 mdf <- data.frame(id,samp1,samp2,samp2a)


> mdf
  id samp1 samp2 samp2a
1  A   100   110    110
2  A   120   130    150
3  C   101   131    151
4  D   110   150    130
5  E   132   122    122
6  F   123   143    143


There are two A ids in this df. I want to select the row with higher mean.

How can I do this.
Thanks
Adrian