```
set.seed(1492)
df <- data.frame(
x = rnorm(100)
)
x <- df$x
base <- ggplot(df, aes(x)) + geom_density()
base + stat_function(fun = dnorm, colour = "red")
base + stat_function(fun = dnorm, colour = "red", args = list(mean = 3))
# Plot functions without data
# Examples adapted from Kohske Takahashi
# Specify range of x-axis
ggplot(data.frame(x = c(0, 2)), aes(x)) +
stat_function(fun = exp, geom = "line")
# Plot a normal curve
ggplot(data.frame(x = c(-5, 5)), aes(x)) + stat_function(fun = dnorm)
# To specify a different mean or sd, use the args parameter to supply new values
ggplot(data.frame(x = c(-5, 5)), aes(x)) +
stat_function(fun = dnorm, args = list(mean = 2, sd = .5))
# Two functions on the same plot
f <- ggplot(data.frame(x = c(0, 10)), aes(x))
f + stat_function(fun = sin, colour = "red") +
stat_function(fun = cos, colour = "blue")
# Using a custom function
test <- function(x) {x ^ 2 + x + 20}
f + stat_function(fun = test)
```

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