drop columns that take less than n values?

Question

Suppose i have a data frame like the following:

df <- data.frame(v1 = sample(1:10, 100, replace = T), v2 = sample(LETTERS, 100, replace = T),
                         


        

Answer 1

Clunky but it works...

x<-as.data.frame(t(apply(df,2,function(x) length(x[unique(x)]))>10))

df[,names(x[,x>0])]