Generally using par(new=T) is more complicated than it is worth, try a different method first. One option is to use the updateusr function from the TeachingDemos package. The first example on the help page shows adding a line to a barplot with everything aligned, follow that example as a start. If that does not do everything you need, then send us a full reproducible example of what you have tried (it makes it easier for us to help you).
Also, creating a barplot with the lower y-limit at any value other than 0 is generally misleading. Hope this helps, -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.s...@imail.org 801.408.8111 > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r- > project.org] On Behalf Of Steve Murray > Sent: Monday, June 15, 2009 11:08 AM > To: r-help@r-project.org > Subject: [R] Aligning axis values when plotting more than one graph on > same axes > > > Dear R Users, > > I am trying to plot a barchart with a line graph superimposed (using > par(new=TRUE)). There are 12 bars and 12 corresponding points for the > line graph. This is fine, except that I'm encountering two problems: > > 1) The position of the points (of the line graph) are not centred on > the middle (horizontally) of each corresponding bar. In fact, whilst > the first point is located on the left-most side of the first bar, > subsequent points drift further towards the right of the bars, until > the final point is at the right-most position on the final bar. I have > used names.arg=substr(month.abb, 1, 1) to represent the first letter of > each month for the barplot and xaxt="n" for the overplotting line > graph. Is there a way of properly aligning the x-axis values so that > the points are centred horizontally on the bars? > > > 2) Similarly, for both plots, I have set ylim=c(10000, 85000) so that > both y-axes are in proportion with one another. However, when I allow > both graphs to plot their y-axis values, it becomes apparent that there > is a slight offset again in where the axis labels are positioned. For > example, 80000 is positioned notably higher up the y-axis for the > barchart than for the line graph. (N.B. I have used xpd=FALSE for the > barchart to prevent bars falling outside of the plot area). How do I > ensure that the y-axis labels are correctly aligned so that they are > common to both graphs? > > Many thanks for your help, > > Steve > > ______________________________________________ > 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.
