Adding text to a plot

问题

x <- seq(-3,3,0.01)
y1 <- dnorm(x,0,1)
y2 <- 0.5*dnorm(x,0,1)
plot(x,y1,type="l",bty="L",xlab="X",ylab="dnorm(X)")
points(x,y2,type="l",col="red")
polygon(c(x,rev(x)),c(y2,rev(y1)),col="skyblue")

I want to label the difference between the two curves at -3, -2, -1, ..., 3. I have tried using just the text function where I manually adjust the coordinates one by one and then type in the difference between the two curves. Is there an more efficient way of doing this so that the difference between the two curves is displayed clearly?

回答1:

x <- seq(-3,3,0.01)
y1 <- dnorm(x,0,1)
y2 <- 0.5*dnorm(x,0,1)
plot(x,y1,type="l",bty="L",xlab="X",ylab="dnorm(X)")
points(x,y2,type="l",col="red")
polygon(c(x,rev(x)),c(y2,rev(y1)),col="skyblue")

idx <- which(x %in% -3:3)
text(x[idx], y1[idx], labels = round(y1[idx], 2))
text(x[idx], y2[idx], labels = round(y2[idx], 2), col="red")

来源：https://stackoverflow.com/questions/34302680/adding-text-to-a-plot