R help - Dec 2015 - change the x axis tickmarks when using plot function in drc package

Looking at the source code of the package drc, there is something that may
somehow explain what
you are experiencing:

file: plot.drc.R, function addAxes(), lines 543-626

ceilingxTicks <- ceiling(log10(xaxisTicks[-1]))
...
xaxisTicks <- c(xaxisTicks[1], 10^(unique(ceilingxTicks)))
....
xLabels <- as.character(xaxisTicks)


I may suggest two options:


1.  provide the x labels at plot() call time:



   plot(mod, type="all", log="x", xtlab = c(-2, -1, 0, 1,
2), xlab="log(dose)")


2.  try to use the option logDose in drm():

      mod <- drm(y~log(dose), fct = LL.4(), logDose=10)
      plot(mod, type="all")

Not sure if that second option fits your needs.


--
GG


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Thanks for your help Giorgio! Both options worked.

2015-12-09 11:46 GMT-05:00 Giorgio Garziano <giorgio.garziano at
ericsson.com>:
> Looking at the source code of the package drc, there is something that may
> somehow explain what
> you are experiencing:
>
> file: plot.drc.R, function addAxes(), lines 543-626
>
> ceilingxTicks <- ceiling(log10(xaxisTicks[-1]))
> ...
> xaxisTicks <- c(xaxisTicks[1], 10^(unique(ceilingxTicks)))
> ....
> xLabels <- as.character(xaxisTicks)
>
>
> I may suggest two options:
>
>
> 1.  provide the x labels at plot() call time:
>
>
>
>    plot(mod, type="all", log="x", xtlab = c(-2, -1, 0,
1, 2),
> xlab="log(dose)")
>
>
> 2.  try to use the option logDose in drm():
>
>       mod <- drm(y~log(dose), fct = LL.4(), logDose=10)
>       plot(mod, type="all")
>
> Not sure if that second option fits your needs.
>
>
> --
> GG
>
>
>         [[alternative HTML version deleted]]
>
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