How can I plot my R Squared value on my scatterplot using R?

Question

This seems a simple question, so I hope its a simple answer. I am plotting my points and fitting a linear model, which I can do OK. I then want to plot some summary statisti

Answer 1

The text function places text into the current plot, it is one option for adding the r-squared value to a plot. Also look at the grconvertX and grconvertY functions for ways to find the location to place the text.

The corner.label and emptyspace functions in the plotrix package may also help.

Answer 2

You can abuse legend() because it has the handy logical placement:

R> DF <- data.frame(VAR1=rnorm(100), VAR2=rnorm(100))
R> with(DF, plot(VAR1, VAR2))
R> abline(fit <- lm(VAR2 ~ VAR1, data=DF), col='red')
R> legend("topright", bty="n", legend=paste("R2 is", 
+         format(summary(fit)$adj.r.squared, digits=4)))

Here bty="n" suppresses the box, and you need format() to shorten the display. Other text() is good, as are arguments main= and sub= to plot().