Find columns with all missing values

Question

I am writing a function, which needs a check on whether (and which!) column (variable) has all missing values (NA, ). The following is fr

Answer 1

To test whether columns have all missing values:

apply(test1,2,function(x) {all(is.na(x))})

To get which columns have all missing values:

  test1.nona <- test1[ , colSums(is.na(test1)) == 0]