On Tue, 2006-08-29 at 13:05 -0700, Dean Sonneborn wrote:> I'm using this syntax to create data subsets for plots:
> subset=source=="Both". Now I would like to create a subset
defined by
> two different variables like this: subset=source=="Both"
> subset=site=="home" but this syntax is not correct. The documents
in the
> manual for subset seem to be creating whole new data files not just
> selecting rows based on the contents of the variables. How do I subset
> based on two variables.
If your data frame is called 'DF':
plot(y ~ x, data = DF, subset = (source == "Both") & (site ==
"home"))
See ?Logic and ?Syntax for more information on creating logical
expressions.
HTH,
Marc Schwartz