[R] Scatter Plot Command Syntax Using Data.Frame Source

[Rich Shepard]

   I've tried various commands. ?plot, Teetor's book, "R Cookbook", and
Mittal's book, "R Graphs Cookbook" without seeing how to write the command
to create scatterplots from my data.frame. The structure is:

> str(chemdata)
'data.frame':	14886 obs. of  4 variables:
  $ site    : Factor w/ 148 levels "BC-0.5","BC-1",..: 104 145 126 115 114
128 124 2 3 3 ...
  $ sampdate: Date, format: "1996-12-27" "1996-08-22" ...
  $ param   : Factor w/ 8 levels "As","Ca","Cl",..: 1 1 1 1 1 1 1 1 1 1 ...
  $ quant   : num  0.06 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 ...

   and what I'd like to do is create scatter plots of quant (y-axis) against
the factor site (x-axis) for specified param factors. Teetor has an example
for a data set with two numeric variables and a single factor. I have a
single numeric veriable, two factors, and a date.

   I'll also want to create time series line plots of values as a function of
date for specified params.

   If the data.frame had only two columns all the examples work. But, using
two columns (the number per site factor for only a specified param factor)
is not covered in what I've read so far.

   Other graphing resources about which I should know?

Rich