Hi In R, using plot(x,y) followed by abline(lm(y~x)) produces a graph with a regression line spanning the whole plot . This means that the line extends beyond the swarm of data points to the defined of default plot region. With par(xpd=T) it will span the entire figure region. But how can I limit a regression line to the data range, i.e between (xmin,ymin) and (xmax,ymax)?
Sorry for not knowing the lingo here. If you don't understand the question, please run the following script: x1<-c(1,2,3,4) x2<-c(5,6,7,8) y1<-c(2,4,5,8) y2<-c(10,11,12,16) plot(x1,y1,xlim=c(0,10),ylim=c(0,20),col="blue") points(x2,y2,col="red") abline(lm(y1~x1),col="blue") abline(lm(y2~x2),col="red") The resulting plot isn't very informative. There is no overlap in the two groups of data, yet the two ablines overlap. I instead want the blue line to go from (1,2) to (4,8) and the red line from (5,10) to (8,16). So, how can I constrain the abline to the relevant region, i.e stop abline from extrapolating beyond the actual range of data. Or should I use a function line 'lines' to do this? Cheers Andres ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html