[R] Proper Syntax for Logical Subset in Subset()

[Rich Shepard]

On Wed, 2 Nov 2011, Rich Shepard wrote:

>  I want a subset of this with only 7 chemicals: Ca, Cl, Cond, Mg, Na, SO4,
> and TDS.

   I should have also written that what I ultimately want is to create a
box-and-whisker plot for these 7 chemicals in a single panel. If that can be
done directly from the source data frame without creating another subset, I
want to learn the syntax for that.

Rich