Legends when plotting a function using stat_function

[daithiquinn]

I'm using the stat_function() command to plot two functions. Is it
possible to have a legend that describes these functions?

## add ggplot2
library(ggplot2)

tmp <- data.frame(x=1:50, y=eq(1:50))

# define equations
eq1 <- function(x) { 10 * exp(x * 0.01 ) }
eq1 <- function(x) { 10 * exp(x * 0.02 ) }

dens = stat_function(fun = eq1, color="red")
high = stat_function(fun = eq2, color="green", alpha=I(1/5))

qplot(x, y, data = tmp,
xlab = "x-axis",
ylab = "y-axis",
main = "title"
) + dens + high

thanks.
David

[Brian Diggs]

Your example is not quite reproducible from what you gave, but see in-
line below for how to make it work.

On Feb 10, 9:02 am, daithiquinn <daithiqu...@gmail.com> wrote:
> I'm using the stat_function() command to plot two functions. Is it
> possible to have a legend that describes these functions?
>
> ## add ggplot2
> library(ggplot2)
>
> tmp <- data.frame(x=1:50, y=eq(1:50))

tmp <- data.frame(x=1:50, y=c(1:50)) # function eq not defined

>
> # define equations
> eq1 <- function(x) { 10 * exp(x * 0.01  ) }
> eq1 <- function(x) { 10 * exp(x * 0.02  ) }

eq2 <- function(x) { 10 * exp(x * 0.02 ) } # almost certain you meant
eq2 here

>
> dens = stat_function(fun = eq1, color="red")
> high = stat_function(fun = eq2, color="green", alpha=I(1/5))

dens <- stat_function(fun = eq1, aes(color="red"))
high <- stat_function(fun = eq2, aes(color="green"), alpha=I(1/5))
# in order for there to be a legend, there must be a scale which means
there must be an aesthetic mapping. Thus the colour specifications go
in an aes()

>
> qplot(x, y,  data = tmp,
>         xlab = "x-axis",
>         ylab = "y-axis",
>         main = "title"
>     )  + dens + high

qplot(x, y, data = tmp,
xlab = "x-axis",
ylab = "y-axis",
main = "title"

) + dens + high +
scale_colour_identity("fits", breaks=c("red","green"),
labels=c("eq1","eq2"))
# defining the colour scale as an identity scale tells it to use the
colors as specified rather than to map two groups to colors in a color
palette.

>
> thanks.
> David

--Brian Diggs