Disable plot display in R

I am trying to turn off the display of plot in R. I read Disable GUI, graphics devices in R but the only solution given is to write the plot to a file. What if I don't want to pollute the workspace and what if I don't have write permission ? I tried `options(device=NULL)` but it didn't work. The context is the package `NbClust` : I want what `NbClust()` returns but I do not want to display the plot it does. Thanks in advance ! edit : Here is a reproducible example using data from the rattle package :) ``` data(wine, package="rattle") df <- scale (wine[-1]) library(NbClust) # This produces a graph output which I don't want nc <- NbClust(df, min.nc=2, max.nc=15, method="kmeans") # This is the plot I want ;) barplot(table(nc$Best.n[1,]), xlab="Numer of Clusters", ylab="Number of Criteria", main="Number of Clusters Chosen by 26 Criteria") ```