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xyplot(): How to Apply Conditional?

5 messages · Rich Shepard, David Winsemius

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The xyplot help page covers several lattice plots and states that with the
exception of xyplot the formula can have the form x ~ y | c. I need to
generate x-y plots for only one of two levels of a conditioning factor. What
is the recommended way to do this?

Rich
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On Oct 17, 2012, at 10:44 AM, Rich Shepard wrote:

            
What exactly is being requested? Do you just need to learn how to use  
the subset parameter? I would not think that the conditioning syntax  
would be used when there were only one level desired.
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On Wed, 17 Oct 2012, David Winsemius wrote:

            
David,

   When I try

xyplot(quant ~ sampdate | era, data = sb.d, main = 'Antimony Concentrations
by Time', ylab = 'Concentration (mg/L)', xlab = 'Time',
subset=era('Pre-Mining'))

this error is returned:

Error in eval(expr, envir, enclos) : could not find function "era"

But, 'era' is a factor in the data frame.

   The syntax above works with bwplot() and I would like to understand why
it's not working with xyplot().

Thanks,

Rich
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On Oct 17, 2012, at 1:29 PM, Rich Shepard wrote:

            
What do you expect when you give xyplot only one panel's worth of data  
and specify a multipanel formula?
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On Oct 17, 2012, at 1:29 PM, Rich Shepard wrote:

            
Furthermore, can you show "working" code that uses a column name as a  
function? That is the error being reported.

Perhaps if you changed to:

subset=era=='Pre-Mining'