[R] one more minor and small bug in lattice in R

[Wladimir Eremeev]

Dear all.

 I have found one more minor bug in the Lattice package.

 When xyplot plots several curves on each panel with the default panel
 function panel.xyplot, and when it is called with "g" %in% type
(that is,
xyplot(y1+y2+y3~x|cond,allow.multiple=TRUE,type=c("o","g"),<other params>)
 ), it draws grid lines several times (for each curve), and it appears,
 that they overlay all curves plotted, except the last one.

 I think there is a need to establish some kind of flag, showing, that
 the grid is already drawn, and other runs of the panel.xyplot for the
 same panel must not draw it again.
 I was looking to the source of the xyplot, but haven't found any place to put the flag.

 Another solution could be to establish separate types for each curve
 on the plot... However, AFAIK, they are not all intercompatible.

 There is also need to do something with custom panel functions...

 Hmm... The task looks complex to me now. :)

 Any suggestions?
 
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Best regards,
Wladimir