Basic Calculations with stat_functions -- Plotting hazard functions - r

Question

I am currently trying to plot some density distributions functions with R's ggplot2. I have the following code:
f <- stat_function(fun="dweibull",
args=list("shape"=1),
"x" = c(0,10))
stat_F <- stat_function(fun="pweibull",
args=list("shape"=1),
"x" = c(0,10))
S <- function() 1 - stat_F
h <- function() f / S
wei_h <- ggplot(data.frame(x=c(0,10))) +
stat_function(fun=h) +
...
Basically I want to plot hazard functions based on a Weibull Distribution with varying parameters, meaning I want to plot:
The above code gives me this error:
Computation failed in stat_function():
unused argument (x_trans)
I also tried to directly use
S <- 1 - stat_function(fun="pweibull", ...)
instead of above "workaround" with the custom function construction. This threw another error, since I was trying to do numeric arithmetics on an object:
non-numeric argument for binary operator
I get that error, but I have no idea for a solution.
I have done some research, but without success. I feel like this should be straightforward. Also I would like to do it "manually" as much as possible, but if there is no simple way to do this, then a packaged solution is just fine aswell.
Thanks in advance for any suggestions!
PS: I basically want to recreate the graph you can find in Kiefer, 1988 on page 10 of the linked PDF file.

Answer 1

Three comments:
stat_function is a function statistic for ggplot2, you cannot divide two stat_function expressions by each other or otherwise use them in mathematical expressions, as in S <- 1 - stat_function(fun="pweibull", ...). That's a fundamental misunderstanding of what stat_function is. stat_function always needs to be added to a ggplot2 plot, as in the example below.
The fun argument for stat_function takes a function as an argument, not a string. You can define functions on the fly if you need ones that don't exist already.
You need to set up an aesthetic mapping, via the aes function.
This code works:
args = list("shape" = 1.2)
ggplot(data.frame(x = seq(0, 10, length.out = 100)), aes(x)) +
stat_function(fun = dweibull, args = args, color = "red") +
stat_function(fun = function(...){1-pweibull(...)}, args = args, color = "green") +
stat_function(fun = function(...){dweibull(...)/(1-pweibull(...))},
args = args, color = "blue")