On Jun 1, 2011, at 7:00 PM, kristina p wrote:
Dear R Team,
I am a new R user and I am currently trying to subset my data under a
special condition. I have went through several pages of the subsetting
section here on the forum, but I was not able to find an answer.
My data is as follows:
ID NAME MS Pol. Party
1 John x F
2 Mary s S
3 Katie x O
4 Sarah p L
5 Martin x O
6 Angelika x F
7 Smith x O
....
Assume this is in a dataframe, 'pol', and that you have corrected the
error in colnames, so that it is Pol_Party. the ave function is
particularly useful when you need to have a vector that "lines up
along side" the other columns
pol[ave(seq_along(pol$ID), pol$Pol_Party, FUN=length) >= 3 , ]
ID NAME MS Pol_Party
3 3 Katie x O
5 5 Martin x O
7 7 Smith x O
(The use of seq_along ensures you will get duplicates of ID that are
in any qualifying Parties.
Another way to generate the values would be to table()-ulate and pick
out the names of qualifying Parties:
> pol[ pol$Pol_Party %in% names(tabl.party)[tabl.party >= 3], ]
ID NAME MS Pol_Party
3 3 Katie x O
5 5 Martin x O
7 7 Smith x O
I am intested in only those observations, where there are at least
three
members of 1 political party. That is, I need to throw out all cases
in the
example above, except for members of party "O".
Both methods use logical indexing with the "[.data.frame" function,
Would really appreciate your help.
--
David Winsemius, MD
West Hartford, CT
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