On Sep 22, 2011, at 6:03 PM, Rich Shepard 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.
Scatterplots are for two variables with continuous valued data. You
are asking about one such variable, apparently within some combination
of groups of discrete variables. Look at dotplot or bwplot examples.
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.
The problem is with the choice of plotting function not fitting the
problem, not with the formula.
--
David Winsemius, MD
West Hartford, CT
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