[R] extract data for specific levels factor

Sarah Goslee
Tue, 25 Oct 2011 19:49:42 -0000

Hi,

2011/10/25 Andr?s Arag?n <armandres at gmail.com>:
> Dear all,
>
> I'm trying to analyze data with the following structure:
>
> ind ? ? ? ? ?cat ? ? ? ? ? ?tx ? ? ?age
> 40.2 por fol peq ? ? vh ? ? ? ?35
> 41.9 por fol med ? ? vh ? ? ? ?35
> 68.9 por fol preov ? vh ? ? ? 35
> 71.5 por fol peq ? ? ?ser ? ? ? 37
> 67.5 ?por fol med ? ?ser ? ? ? 37
> 76.9 ?por fol preov ? ser ? ? 37
> 78.7 ?por fol peq ? ? ?otr ? ? ?37
> 78.3 ?por fol med ? ?otr ? ? ? 37
> 82.1 ?por fol preov ? otr ? ? ?37
> 83.9 ?por fol peq ? ? ?vh ? ? ? 37
> 80.6 ?por fol med ? ? ?vh ? ? ?37
> 76.1 ?por fol preov ? ? vh ? ? 37
> 86.9 ?por fol peq ? ? ? ?ser ? ? 35
> 97.7 ?por fol med ? ? ? ser ? ? 35
> 62.3 ?por fol preov ? ? ser ? ? 35
>
>
>
> I want to separate exclusively some of factor levels ?(?por fol peq?
> in the ?cat? colum). I am using ggplot2 ?and I only can plot all of
> factors, not separately. I did try ddply without success.
> Any help is welcome.

This kind of question is *so* much easier to answer if you provide
reproducible data with dput(). This is untested because of lack of
data, but what about

newdata <- origdata[origdata$cat %in% c("por", "fol",
"peq"),]

Depending on the effect you want, you may also wish to drop the
unused levels or reorder the levels using factor().

Sarah

--
Sarah Goslee