How to subset() from data frame using specific rows

Hi Rich,

On Tue, 4 Oct 2011, Sarah Goslee wrote:

You can use something like this:

testdata <- c("A1", "A2", "A3", "B1", "B2", "B3")
grep("^A", testdata)

[1] 1 2 3

grepl("^A", testdata)

[1] ?TRUE ?TRUE ?TRUE FALSE FALSE FALSE

Sarah,

?I don't see how this gives me a data frame containing only those sites I
specify. I want to plot by sites-within-streams specifying which param
factor to use.

You asked for pointers, and didn't provide a reproducible example, so
I offered a
pointer.

If you have a logical vector that specifies whether to include or omit
a row, you
can use that to subset your data frame.

sitesToUse <- grepl("firstsite", mydata$mysitenames)
dataframeForThatSite <- mydata[sitesToUse, ]

If you want real worked results, you'll need to provide a reproducible example
of your own.

Sarah

Sarah Goslee
http://www.functionaldiversity.org