[R] Retain only those records from a dataframe that exist in another dataframe
p.dalgaard at biostat.ku.dk
Mon Aug 7 22:14:05 CEST 2006
"Mark Na" <mtb954 at gmail.com> writes:
> Dear R community,
> I have two dataframes "first" and "second" which share a unique identifier.
> I wish to make a new dataframe "third" retaining only the rows in
> "first" which also occur in "second".
> I have tried using merge but can't seem to figure it out. Any ideas?
Doesn't sound like a merge problem. Will this do it?:
first[first$ID %in% second$ID,]
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c/ /'_ --- Dept. of Biostatistics PO Box 2099, 1014 Cph. K
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~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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