[R] Adjusting axis labels on lattice xyplot

[Rich Shepard]

On Fri, 14 Oct 2016, David Winsemius wrote:

> xyplot(amount ~ date | station, data=rain, main="Weather Stations",
>   xlab="Date", ylab="Amount (inches)", pch=16, col=132,
>   scales=list(y=list(at=0:4),
>               x=list(at=seq(min(rain$date), max(rain$date), by='week'), rot=90) )
>     )

David,

   I searched ?xyplot for the 'by' option in scales and did not find it. I
understand the other parameters of scales and would like to learn how to use
'by' when appropriate.

TIA,

Rich