ggplot2 (version 0.9.0)

stat_function: Superimpose a function.

Description

Superimpose a function.

Usage

stat_function(mapping = NULL, data = NULL, geom = "path",
    position = "identity", fun, n = 101, args = list(),
    ...)

Arguments

fun

function to use

n

number of points to interpolate along

args

list of additional arguments to pass to fun

mapping

The aesthetic mapping, usually constructed with aes or aes_string. Only needs to be set at the layer level if you are overriding the plot defaults.

data

A layer specific dataset - only needed if you want to override the plot defaults.

geom

The geometric object to use display the data

position

The position adjustment to use for overlappling points on this layer

...

other arguments passed on to layer. This can include aesthetics whose values you want to set, not map. See layer for more details.

Value

• a data.frame with additional columns:
• x
  x's along a grid
• y
  value of function evaluated at corresponding x

Examples

x <- rnorm(100)
base <- qplot(x, geom = "density")
base + stat_function(fun = dnorm, colour = "red")
base + stat_function(fun = dnorm, colour = "red", arg = list(mean = 3))

# Plot functions without data
# Examples adapted from Kohske Takahashi

# Specify range of x-axis
qplot(c(0, 2), stat = "function", fun = exp, geom = "line")
ggplot(data.frame(x = c(0, 2)), aes(x)) + stat_function(fun = exp)
# Plot a normal curve
ggplot(data.frame(x = c(-5, 5)), aes(x)) + stat_function(fun = dnorm)
# With qplot
qplot(c(-5, 5), stat = "function", fun = dnorm, geom = "line")
# Or
qplot(c(-5, 5), geom = "blank") + 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)