[R] Bivariate Scatter Plots with Lattice

[Dennis Murphy]

Hi:

Question: Do you want 37 different panels with plots of quant vs. date
by param, or two panels (one per chemical) with all 37 streams? If you
only want two of the eight chemicals, I'd suggest using subset() to
select out the pair you want and then redefine the param factor so
that the subset data frame has two factor levels instead of eight.
Since there are several ways to interpret 'in which there are data',
you might want to expound a little further about your intentions in
that regard.

HTH,
Dennis

On Thu, Sep 22, 2011 at 3:03 PM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
>  Data frame has this structure:
>
> 'data.frame':   11169 obs. of  4 variables:
>  $ stream  : Factor w/ 37 levels "Burns","CIL",..: 1 1 1 1 1 1 1 1 1 1 ...
>  $ sampdate: Date, format: "1987-07-23" "1987-09-17" ...
>  $ param   : Factor w/ 8 levels "As","Ca","Cl",..: 1 1 1 1 1 1 1 1 1 1 ...
>  $ quant   : num  0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0 ...
>
>  I want to create scatter plots of the concentrations (numeric column
> 'quant') for two specified chemicals (factor column 'param') for all dates
> and streams (factor column 'stream') in which there are data.
>
>  Looking in ?lattice and Deepayan's book did not provide an example. I've
> tried varies formulae but without success, and would appreciate a pointer to
> documentation and examples of how to write such an expression.
>
> Rich
>
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