text_combined: baptiste auguie ba208exeteracuk hi list basic question lattice wish add vertical lines panel xyplot demonstrated example librarylattice xx seq1 10 length100 x repxx 4 ccosxx sinxx xx xx210 fact factorrepccos sin id square each100 fact2 factorrepcperiodic periodic each100 mydf dataframexx yy fact fact fact2 fact2 headmydf xyplotyx fact data mydf groups fact2 plots expected mylines c5 6 want draw vertical lines according level fact2 xyplotyx fact data mydf groups fact2 panelfunctionx ysubscripts panelxyplotx ysubscripts panelablinevmylinessubscripts gives error dont understand help panel function alternatively tried ggplot get error p ggplotmydf aesx geom_pathaescolour fact facet_gridfact2 fact geom_vlineintercept mylines select relevant one p many thanks baptiste _____________________________ baptiste auguié school physics university exeter stocker road exeter devon ex4 4ql uk phone 44 1392 264187 httpnewtonexacukresearchemag ______________________________________________ rhelprprojectorg mailing list httpsstatethzchmailmanlistinforhelp please read posting guide httpwwwrprojectorgpostingguidehtml provide commented minimal selfcontained reproducible code thu 07 aug 2008 195406 0100 r lattice add vertical lines xyplot