R : remove columns from dataframe where ALL values are NA

Answer 1

Try this:

df <- df[,colSums(is.na(df))<nrow(df)]

Answer 2

Another way would be to use the apply() function.

If you have the data.frame

df <- data.frame (var1 = c(1:7,NA),
                  var2 = c(1,2,1,3,4,NA,NA,9),
                  var3 = c(NA)
                  )

then you can use apply() to see which columns fulfill your condition and so you can simply do the same subsetting as in the answer by Musa, only with an apply approach.

> !apply (is.na(df), 2, all)
 var1  var2  var3 
 TRUE  TRUE FALSE 

> df[, !apply(is.na(df), 2, all)]
  var1 var2
1    1    1
2    2    2
3    3    1
4    4    3
5    5    4
6    6   NA
7    7   NA
8   NA    9