Dear Group,
I am working with a large dataset where I need to select for each unique id
the the unique lastpk row. Here is a sample subject:
id wtdt wt lastpk
64050256 2010-09-18 275 2010-09-16
64050256 2010-09-19 277 2010-09-18
64050256 2010-09-20 272 2010-09-18
64050256 2010-09-21 277 2010-09-18
I want the result as:
id wtdt wt lastpk
64050256 2010-09-18 275 2010-09-16
64050256 2010-09-19 277 2010-09-18
I am using !(duplicated(data$id)) to select the first row but now I want to
select the first row of the unique lastpk in each unique id.
I appreciate your help on this.
Regards,
Ayyappa
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