[R] adding labels to a multiple plot in lattice

[Jorge Ahumada]

Hello,

I am trying to a create a plot in lattice that has four panels, but  
all of them have the same xlab and ylab, so instead of labeling each  
plot  separately I want to create one single label for the y series  
and one for the x series, somehow along the left and bottom margins  
of the plot. Can anybody help? This is the pseudocode:

print(xyplot(x1~y1),split=c(1,1,2,2),more=T)
print(xyplot(x2~y2),split=c(2,1,2,2),more=T)
print(xyplot(x3~y3),split=c(1,2,2,2),more=T)
print(xyplot(x4~y4),split=c(2,2,2,2))

thanks,

Jorge