[R] Using latticeExtra as.layer function with different number of plot panels

[David Winsemius]

On Jul 30, 2015, at 8:37 AM, sbihorel wrote:

> Hi,
> 
> When the as.layer function is used to overaly 2 lattice plots, there seems to be an assumption that the data used in both plots will generate the same number of panels (and, I believe, in the same order). In case the data used in the plot within the as.layer call is incomplete , data may be plotted on the "wrong" panel, and data seem to get re-used on the last panel(s). See what happens in the example code below when the records with state.region=="South" are dropped...
> 
> Is there a trick to overlay panel based upon the conditioning variable value rather than the panel order?
> 
> require(lattice)
> require(latticeExtra)
> state2 <- state <- data.frame(state.x77,state.region)
> state2$Income <- sample(state2$Income)
> state3 <- state2[which(state2$state.region!="South"),]
> foo <- xyplot(Income~Population|state.region,data=state,main='foo')
> foo
> 
> bar <- update(foo,main='bar') + as.layer(xyplot(Income~Population|state.region,data=state2,col='red'))
> bar
> 
> bar2 <- update(foo,main='bar2') + as.layer(xyplot(Income~Population|state.region,data=state3,col='red'))
> bar2

I don't know if this works using the `+.lattice` function but it is possible to selectively update panels using `trellis.focus`

-- 
David.
> 
> Thank you
> 
> Sebastien
> 
> PS: I know that I could get what I want by setting the Income variable to NA for records with state.region=="South" instead of dropping them... but this is not the point of my example. I am just trying to illustrate what happens when as.layer is used for plotting data with inconsistent dimensions.
> 
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David Winsemius
Alameda, CA, USA