How to add a line (abline e.g.) into a plot in a loop function in R

Question

I have a dataset in which I need to plot each variable. I made a loop for this since the dataset contains like 50 variables. This is what I got thus far:

invisible(lapply(colnames(Data),function(x){
plot(Data[,x],main=x,type="l", xlab= 'Week number', ylab='Amount')
}))

This automatically plots all the variables in my dataset in separate plots. However, I need to plot lines in all of these plots. The idea is that I add an average line for each x. So a horizontal line on the height whichs corresponds to the value of the mean x. I tried to do this by adding the abline(h=mean(x)) function to the function above but this doesn't work. Do you guys have any ideas on how to do this?

Answer 1

you should use

abline(h=mean(Data[,x]))

not

abline(h=mean(x)) 

since each time x is a colnames. to check use this code

Data<-matrix(sqrt(1:20),ncol=4)
colnames(Data)<-c(letters[1:4])
par(mfrow=c(2,2))

invisible(lapply(colnames(Data),function(x){
plot(Data[,x],main=x,type="l", xlab= 'Week number', ylab='Amount')
abline(h=mean(Data[,x]))
}))