[R] subsetting data by specified observation number

[Linh Tran]

Hi members,

I'd like to thank you guys ahead of time for the help. I'm kind of stuck.

I have a data frame with ID and position numbers:
1> head(failed.3)
         id position
1  10000997        2
4  1000RW_M        2
15 1006RW_G        2
24 1012RW_M        3
28 10160917        2
30 1016RW_M       13

I'd like to use this to subset out a large dataset and keep only the
observation number corresponding to the position number. So for example,
ID 10000997 has 10 observations. I want to keep the 2nd one only.


Thanks,

-linh