Hi Kimmo, You can try to use the "layer" function from "latticeExtra" library:
densityplot(~PV1CIV, groups=SGENDER, data=ISGFINC2, lwd=2, col=1, lty=c(1,2), pch=c("+","o"), key=list(text=list(lab=levels(ISGFINC2$SGENDER), col=1), space="bottom", columns=2, border=T, lines=T, lwd=2, lty=c(1,2), col=1), ref=T, plot.points=F) + layer(panel.abline(v=mean(PV1CIV[ SGENDER==1 ]))) Regards, Pascal ----- Mail original ----- De : K. Elo <mailli...@nic.fi> À : r-help@r-project.org Cc : Envoyé le : Jeudi 8 mars 2012 16h35 Objet : [R] Adding mean line to a lattice density plot Hi! I have used the following command: densityplot(~PV1CIV, groups=SGENDER, data=ISGFINC2, lwd=2, col=1, lty=c(1,2), pch=c("+","o"), key=list(text=list(lab=levels(ISGFINC2$SGENDER), col=1), space="bottom", columns=2, border=T, lines=T, lwd=2, lty=c(1,2), col=1), ref=T, plot.points=F) to produce a lattice density plot presenting the distribution of achievment points grouped by the gender of the respondents. Now, in order to clarify the difference between boys and girls, I would like to add two vertical lines: one for the mean of boys, the other for the mean of girls. How could I do this (I have tried to use the function 'panel.abline', but could not figure out how to define the correct x-axis point (using 'v=mean(PV1CIV[ SGENDER==1 ])' as a parameter is not working...). Thanks in advance, Kimmo ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.