I've looked through some other threads and tried using expression and bquote but without any luck. I'm a beginner with R and would appreciate help with this specific example. I've found the following code on another website and it is working for me, but I can't make the 2 in R2 a superscript.
This is the initial code:
ggplotRegression <- function (fit) {
require(ggplot2)
ggplot(fit$model, aes_string(x = names(fit$model)[2], y = names(fit$model)[1])) +
geom_point() +
stat_smooth(method = "lm") +
labs(title = paste("R2 = ",signif(summary(fit)$r.squared, 5),
"Intercept =",signif(fit$coef[[1]],5 ),
" Slope =",signif(fit$coef[[2]], 5),
" P =",signif(summary(fit)$coef[2,4], 5)))
}
ggplotRegression(lm(TOA_NDVI ~ Field_NDVI, data = NDVI_type))
This is one of the things I've tried:
ggplotRegression <- function (fit) {
require(ggplot2)
ggplot(fit$model, aes_string(x = names(fit$model)[2], y = names(fit$model)[1])) +
geom_point() +
stat_smooth(method = "lm") +
labs(title = paste(expression("R^2 *="),signif(summary(fit)$r.squared, 5)),
"Intercept =",signif(fit$coef[[1]],5 ),
" Slope =",signif(fit$coef[[2]], 5),
" P =",signif(summary(fit)$coef[2,4], 5)))
}
ggplotRegression(lm(TOA_NDVI ~ Field_NDVI, data = NDVI_type))
Any help would be very much appreciated. Thank you.

dput(NDVI_type)and paste the output in your question, others can easily access your data and run your code. As it is now, nobody can run this without having your data already.