Dear all



 I am trying to make an interaction plot among 6 variables; e.g. PH to be in the x axis and the rest 5 variables in the y axis. The code that I am using is the below:



The name of my file is e.g. spec so



> spec<-read.csv("spec.csv")

>head (spec)

>str(spec)

>names<-names(spec)[2:6]
>speclong <- reshape(spec, idvar = "id", varying = list(names), v.names="outcome",direction = "long")

>speclong$time2<-factor(speclong$time,labels=rep("   ",5))

>interaction.plot(speclong$PH,speclong$time2,speclong$outcome, xaxt="n", type="l", log="y", trace.label="",col=rainbow(8))



what I want is to change the labels of the x axis. If for example I don't use xaxt="n", by default it shows some values of PH e.g. 4.93, 5.97, 6.23, 6.47, 6.59, 6.77, 6.89, 7.35 but it don't show the ticks in each value. However I would like to define the x values e.g. 5.0, 5.5, 6.0, 6.5, 7.0. I used the xlim but it says error as well

>axis(1, at=c(5.0, 5.5, 6.0, 6.5, 7.0)) but still there is a problem.



Does anyone know how I can define that?



Thank you in advance.



Kind regards

Maria

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