[R] change the x axis tickmarks when using plot function in drc package

[li li]

Hi all,
  When plotting the dose response curve using plot function as in the
example codes below, the scale of the axis should really be on the log
scale of the dose given the shape of the graph. But as you can see, the
tickmarks of the returned graph represent the original scale. How can I
change the tick marks to the scale that the correspond to log(dose)?
  Thanks much in advance.
    Hanna


dose <- rep(50*2^(-(0:11)),3)
dose
d <- 100
c <- 1
b <- 1
e <- 1.6
y <- rnorm(length(dose))+ c+ (d-c)/(1+exp(b*(log(dose)-log(e))))
library(drc)
mod <- drm(y~dose, fct = LL.4())
summary(mod)
plot(mod, type="all")

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