[R] subsetting with condition

[Bert Gunter]

Kristina:

You posed your question nicely, but it would help R HelperRs if you
used dput() to post your data for us to more easily copy and paste
into R in future.

Anyway, there are probably about a million ways to do this (see
especially the ddply package for organizing data), but one basic
approach is to use table() to count Pol. parties (a bad name for a
variable, btw, as the space requires backtick quoting) and then use
the names attribute of the result to identify the parties you want.
i.e.

tbl <- table(polParties)
names(tbl[tbl>3])  ## gives the names of polParties with > 3 entries.

Then use subset (or indexing) on these with %in%

etc.

-- Bert

On Wed, Jun 1, 2011 at 4:00 PM, kristina p <puzarina.k at gmail.com> 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
> ....
>
> 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".
>
> Would really appreciate your help.
> K
>
> --
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>
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>



-- 
"Men by nature long to get on to the ultimate truths, and will often
be impatient with elementary studies or fight shy of them. If it were
possible to reach the ultimate truths without the elementary studies
usually prefixed to them, these would not be preparatory studies but
superfluous diversions."

-- Maimonides (1135-1204)

Bert Gunter
Genentech Nonclinical Biostatistics
467-7374
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm