baptiste auguie ba208exeteracuk many thanks deepayan works nicely always need simple examples understand help page reason also hadley cant get example ggplot2s website work slopes intercepts data p ggplotmtcars aesx wt ympg cyl geom_point df dataframearnorm10 25 brnorm10 0 p geom_ablineaesintercepta slopeb datadf get error error dataframedf var undefined columns selected thanks baptiste 7 aug 2008 2004 deepayan sarkar wrote thu aug 7 2008 1154 baptiste auguie wrote 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 think meant xyplotyx fact data mydf groups fact2 panel functionx subscripts groups panelxyplotx subscripts subscripts groups groups g uniqueasnumericgroupssubscripts panelablinev mylinesg another approach xyploty x fact data mydf groups fact2 panel panelsuperpose panelgroups function groupnumber panelablinev mylinesgroupnumber panelxyplot deepayan _____________________________ 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 214212 0100 r lattice add vertical lines xyplot