Here is a simple but useful function for adding text to a plot device using the relative

*x*,

*y*coordinates (

*i.e.*between 0 and 1). I found myself programming these few lines repeatedly and decided to finally bundle it into a function, called

*reltext()*. The function can be found below, and is also available in the

*sinkr*package (https://github.com/marchtaylor/sinkr).

Example 2:

Example 3:

**Script to reproduce the examples:**

reltext <- function(relx=0.5, rely=0.5, labels = seq_along(relx), ...){ usr <- par("usr") x <- usr[1] + relx*(usr[2]-usr[1]) y <- usr[3] + rely*(usr[4]-usr[3]) text(x, y, labels, ...) } set.seed(1) n <- 100 a <- 3 b <- 5 x <- rnorm(n) y <- a + b*x + rnorm(n, sd=2) fit <- lm(y ~ x) png("reltext_ex1.png", width=3.5, height=3.5, units="in", res=300, family="Arial", type="cairo") op <- par(mar=c(3,3,0.5,0.5), mgp=c(1.5,0.5,0), tcl=-0.25, las=1, bty="l") plot(x, y) abline(fit, lty=2, col=4) reltext(0, 0.95, pos=4, col=4, labels=bquote( italic(y) == .(sprintf("%0.2f", (coef(fit)[1])))+.(sprintf("%0.2f", (coef(fit)[2])))~"*"~italic(x) ) ) reltext(0, 0.85, pos=4, col=4, labels=bquote( bolditalic(R)^2 == .(round(summary(fit)$adj.r.squared,2)) ) ) par(op) dev.off() png("reltext_ex2.png", width=3.5, height=3.5, units="in", res=300, family="Arial", type="cairo") op <- par(mar=c(4,4,1,1)) plot(x, y) abline(fit, lty=2, col=8) reltext(c(0,0.95), c(0.95, 0.05), pos=c(4,2), col=c(3,4), labels=c("text1", "text2")) par(op) dev.off() png("reltext_ex3.png", width=3.5, height=3.5, units="in", res=300, family="Arial", type="cairo") op <- par(mar=c(4,4,1,1), ps=8) plot(x, y, t="n") reltext(0.1, labels="text", pos=1, col=1) reltext(0.1, labels="text", pos=2, col=2) reltext(0.1, labels="text", pos=3, col=3) reltext(0.1, labels="text", pos=4, col=4) reltext(0.9, labels="text", pos=1, col=1) reltext(0.9, labels="text", pos=2, col=2) reltext(0.9, labels="text", pos=3, col=3) reltext(0.9, labels="text", pos=4, col=4) reltext(0.1, 0.9, labels="text", pos=1, col=1) reltext(0.1, 0.9, labels="text", pos=2, col=2) reltext(0.1, 0.9, labels="text", pos=3, col=3) reltext(0.1, 0.9, labels="text", pos=4, col=4) reltext(0.9, 0.1, labels="text", pos=1, col=1) reltext(0.9, 0.1, labels="text", pos=2, col=2) reltext(0.9, 0.1, labels="text", pos=3, col=3) reltext(0.9, 0.1, labels="text", pos=4, col=4) par(op) dev.off()

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