绘图：R：图例定位（单位）+字体

Question

I have the following

xaxis <- seq(0,1,by=0.01)
aij <- sqrt(1 - (1-xaxis)**1.02)
bij <- 1 - (1 - xaxis)**1.50 
cij<-aij-bij
pdf("MyPdf.pdf",family="Times New Roman")
par(mfrow=c(1, 1), mar=c(5, 5, 4, 10))
plot(xaxis,aij,type="l", col="black",lty=1, xlab="Size ratio", ylab="Value of function")
lines(xaxis,bij,type="l",col="black",lty=2)
par(new=TRUE)
plot(xaxis,cij,,type="l",col="black",lty=4,xaxt="n",yaxt="n",xlab="",ylab="")
grid(nx = 10, ny = 10)
axis(4)
mtext("Difference", side=4,line=3)
legend(x='bottomright',col=c("black","black"), lty=c(1,2,3), legend=c("aij","bij","Difference"),inset=c(-0.25,0))
dev.off()

I am not able to understand the following:

1. How to specify the coordinates for the legend (for example instead of bottomright I wish to have a personally chosen position) - What are the units for the coordinate system and what is its orientation?
2. How to position the text properly?
3. Is it possible to have BOLD, TIMES font in this plot for all the objects?

Answer 1

This illustrates how to move the legend to a particular location in the coordinate system of the plot, with "user-coordinates". See ?par for how to provide the proper value to 'text.font' in the ?legend function. My pdf-device has only a "Times" font, so I cannot show you how to use the named font you describe. You can see the valid names of the currently available pdf fonts with:

names(pdfFonts())

pdf("MyPdf.pdf", family="Times")
par(mfrow=c(1, 1), mar=c(5, 5, 4, 10))
plot(xaxis,aij,type="l", col="black",lty=1, xlab="Size ratio", ylab="Value of function")
lines(xaxis,bij,type="l",col="black",lty=2)
par(new=TRUE)
plot(xaxis,cij,,type="l",col="black",lty=4,xaxt="n",yaxt="n",xlab="",ylab="")
grid(nx = 10, ny = 10)
axis(4)
mtext("Difference", side=4,line=3)
legend(x=0.2,y=0.02, col=c("black","black"), lty=c(1,2,3), legend=c("aij","bij","Difference"), text.font=2 )
dev.off()