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So I am trying to add a simple equation to my graph using the text function in R but for some reason its not working.

This is how I generated my randon simulated data:

a <- 5 b <- 7 sigma <- 3 x <- runif(100, min = 0, max = 50) n <- length(x) y <- a + b * x + rnorm(n, 0, sigma) fakeData <- data.frame(x, y)

Then I plugged in the data frame and added a regression line like so.

ggplot(data = fakeData, aes(y, x)) + geom_point() + geom_smooth(method = 'lm', se = FALSE) + labs(x = "random uniform distribution from range 0 - 50.", y = "Linear model points based on the Uniform dist", title = "Fake data simulation")

Which results in a graph like this

enter image description here

Now all I want to do is add the equation of the line to the graph using the text function but for some reason, R just seems to be throwing errors at me. I tried googling the issue but I wasnt able to resolve it. I tried this method also but the lack of documentation is appalling I have no idea what the guy was doing in the function.

enter image description here

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  • Did you meant geom_text ? Commented Oct 25, 2020 at 20:34
  • text() is a base R graphics function and cannot be used with ggplot. I would encourage you to use the answer at the duplicate you already identified: stackoverflow.com/questions/7549694/…. I'm not sure which answer was appalling, but there are a few answers there. Commented Oct 25, 2020 at 20:34
  • @akrun See that's what I thought but my textbook specifically mentions using the text function to display the equation. Commented Oct 25, 2020 at 20:36
  • Well, text() would work if you were just using base plot() but you are not. There are different methods required if you are using base R graphics vs ggplot graphics and you basically can't combine them. It's unclear what your textbook may have intended. Commented Oct 25, 2020 at 20:38
  • @MrFlick I kid you not this textbook is a mess...For some reason, it has like 4.9 stars but it's so disorganized it's called Statistical Regression and other stories if youre curious. Commented Oct 25, 2020 at 21:25

1 Answer 1

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Try this with annotate() but you previously have to obtain the coefs model using lm():

library(ggplot2) #Code a <- 5 b <- 7 sigma <- 3 x <- runif(100, min = 0, max = 50) n <- length(x) y <- a + b * x + rnorm(n, 0, sigma) fakeData <- data.frame(x, y) #lm mod <- lm(y~x,data=fakeData) lab <- paste0(round(coef(mod)[1],3),'+',paste0(round(coef(mod)[2],3),'x')) #plot ggplot(data = fakeData, aes(y, x)) + geom_point() + geom_smooth(method = 'lm', se = FALSE) + labs(x = "random uniform distribution from range 0 - 50.", y = "Linear model points based on the Uniform dist", title = "Fake data simulation")+ annotate(geom='text',x=50,y=30,label=lab,fontface='bold')

Output:

enter image description here

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