I get only 'NA' values into my loop - Need to find mean of max CR_Art per Experiment per Mussel

Question

[jeff.roemer]

Importing datafile "Raadata.csv" (Headers: Treatment, Mussel, Experiment, Interval, CR_Art, CR_Rho, CHR_Art, FR_C_Art , CHR_Rho, FR_C_Rho). Some fields are empty. Not all treatments have values in all columns. read.csv2 is used because of European standards, I have to convert comma to dot:

Max_CR_FR <- read.csv2(file="Raadata.csv", header=T, sep=";",skipNul=TRUE)

Grouping data by Mussel & Experiment:

Max_CR_FR$Group= factor(paste(Max_CR_FR$Mussel, Max_CR_FR$Experiment))

Selecting on treatment and de-selecting CR_Art with NA:

Art=subset(Max_CR_FR, Treatment=="Artemia" & !is.na(Max_CR_FR$CR_Art))

Everything works fine until here at least.

Calculating the mean of maximum values of CR_Art for each group:

F<-function(Data){
Exp_max=tapply(Data$CR_Art, Data$Group, max, na.rm=TRUE)
mean(Exp_max)
}

Bootstrapping:

boots=list()
for(i in 1:1000) boots[[i]]=Art[ sample.int(nrow(Art),replace=TRUE) ,]
means= lapply( boots, F)
meanstab = do.call(rbind,means)

Confidence interval:

apply(meanstab,2,quantile,probs=c(0.025,0.975),na.rm=TRUE)

[PoGibas]

Show head of your original csv data.