If you can change the line colour try this options(mgp=c(2,0.5,0),cex.lab=1.6)
plot(df1$B, predict(regressor,df1), type="l", col="grey", lwd=2, lty=1, xlim=range(c(1.2,1.7)), ylim=rev(range(c(-19,-8)))) lines(df1$B,as.numeric(df1$A), type="p", col="black", cex=2, pch=17) box(lwd=3) Saves typing by using options Regards Duncan Duncan Mackay Department of Agronomy and Soil Science University of New England Armidale NSW 2350 -----Original Message----- From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of jean-philippe Sent: Tuesday, 5 December 2017 04:14 To: R mailing list Subject: [R] problem with the behaviour of dashed lines in R plots dear R users, I am performing a linear regression with lm, and I would like to plot the regressor in dashed lines. I know that the lty=2 option is the way out, but it has a very strange behaviour: the line starts dashed but then the spaces between each dash becomes very tiny and so the line become somehow continuous for the human eye. Do you know how to fix that problem, in order to have a dashed line with big enough spaces between the dashes? Here is a MWE (don't mind if clearly a linear model will not fit these "fake randomly generated" data). Also, changing the plot(...,type="l") to abline(regressor,lty=2,...) helps and draw a pure dashed line but it is impossible to force it to stay in the bounds of the data. Changing to line instead shows the same problem as mentioned here in the MWE. pdf("reproducableex.pdf") df1<-data.frame(B=runif(20,1.4,1.6),A=runif(20,-19.5,-9.8)) regressor<-lm(A~B,data = df1) plot(df1$B,predict(regressor,df1),type="l", col="black", mgp=c(2,0.5,0),cex.lab=1.6, lwd=2, lty=2,xlim=range(c(1.2,1.7)),ylim=rev(range(c(-19,-8)))) par(new = TRUE) plot(df1$B,as.numeric(df1$A),type="p", col="black", mgp=c(2,0.5,0),cex.lab=1.6,cex=2, xlab = "", ylab = "",xlim=range(c(1.2,1.7)),ylim=rev(range(c(-19,-8))),pch=17) box(lwd=3) dev.off() Thanks in advance, best regards Jean-Philippe Fontaine -- Jean-Philippe Fontaine PhD Student in Astroparticle Physics, Gran Sasso Science Institute (GSSI), Viale Francesco Crispi 7, 67100 L'Aquila, Italy Mobile: +393487128593, +33615653774 ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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 -- To UNSUBSCRIBE and more, see 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.