Search code examples
rplotggplot2normal-distributionstandard-deviation

How to draw normal distribution graph with two standard deviation in R

I am new in R and would like to plot a normal distribution graph where the region of two standard deviation is selected by arrows, exactly as shown below.

enter image description here

Solution

  • This question lacks the effort but it piqued my interest, so there you have it:

    #standard normal distribution data
x <- seq(-4, 4, length=100)
hx <- dnorm(x)

#plot a standard normal distribution
plot(x, hx, type="l", lty=2, xlab="x value")
#plot a vertical line at -2*std
abline(v=-2, col='red')
#plot a vertical line at  2*std
abline(v= 2, col='red')
#make the arrow
arrows(x0=-2, y0=0.35, x1=2, y1=0.35, code=3, col='blue')
#plot the text
text(x=0, y=0.37,labels='95%', col='red')

    Result:

    enter image description here