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Thanks for flagging up the 'segments' command. However=2C I'm having troubl= e getting it to work - this is probably due to me misunderstanding the docu= mentation for this command. The plot section of my script appears as follows: test3 <- 36:45 plot(data_means=2C type=3D"b"=2C pch=3D4=2C ylab=3D""=2C xlab=3D""=2C xaxt= =3D"n"=2C yaxt=3D"n"=2C col=3D3=2C ylim=3Dc(250=2C380)) abline(lm(data_means[36:45] ~ test3)=2C lty=3D2) As you can see=2C I'm only plotting points 36 to 45 from the object 'data_m= eans'. This intentionally results in much white space along the x-axis unti= l point 36 is reached. However=2C when inserting the trendline=2C this runs= along the entire length of the x-axis instead of just through points 36 to= 45. Ideally=2C a line which slightly overshoots the data subset would look= the best=2C but one constrained to the extents of the 36:45 would also do = the job just fine. So=2C my question is=2C how do I use 'segments' (or otherwise) to create a = linear trendline which only extends through points 36:45? (and overshoots a= t either end very slightly=2C if possible=2C rather than running along the = entire length of the x-axis). Many thanks again=2C Steve ---------------------------------------- > CC: r-help@r-project.org > From: dwinsem...@comcast.net > To: smurray...@hotmail.com > Subject: Re: [R] Trendline for a subset of data > Date: Fri=2C 9 Oct 2009 09:27:43 -0400 > > > On Oct 9=2C 2009=2C at 5:50 AM=2C Steve Murray wrote: > >> >> Dear all=2C >> >> I am using abline(lm ...) to insert a linear trendline through a >> portion of my data (e.g. dataset[=2C36:45]). However=2C I am finding >> that whilst the trendline is correctly displayed and representative >> of the data portion I've chosen=2C the line continues to run beyond >> this data segment and continues until it intersects the vertical >> axes at each side of the plot. >> >> How do I display the line so that it only runs between point 36 and >> 45 (as shown in the example above) as doesn't continue to display a >> line throughout the rest of the plot space? >> > > ?segments > >> Many thanks=2C >> >> Steve >> > > David Winsemius=2C MD > Heritage Laboratories > West Hartford=2C CT > =0A= _________________________________________________________________=0A= View your other email accounts from your Hotmail inbox. Add them now.=0A= ______________________________________________ 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.