[R] xyplot(): How to Apply Conditional?
dwinsemius at comcast.net
Wed Oct 17 22:37:49 CEST 2012
On Oct 17, 2012, at 1:29 PM, Rich Shepard wrote:
> On Wed, 17 Oct 2012, David Winsemius 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.
> When I try
> xyplot(quant ~ sampdate | era, data = sb.d, main = 'Antimony
> by Time', ylab = 'Concentration (mg/L)', xlab = 'Time',
> 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
> it's not working with xyplot().
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:
David Winsemius, MD
Alameda, CA, USA
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