R: Remove multiple empty columns of character variables

Question

I have a data frame where all the variables are of character type. Many of the columns are completely empty, i.e. only the variable headers are there, but no values. Is there any way to subset out the empty columns?

Answer 1

If your empty columns are really empty character columns, something like the following should work. It will need to be modified if your "empty" character columns include, say, spaces.

Sample data:

mydf <- data.frame(
  A = c("a", "b"),
  B = c("y", ""),
  C = c("", ""),
  D = c("", ""),
  E = c("", "z")
)
mydf
#   A B C D E
# 1 a y      
# 2 b       z

Identifying and removing the "empty" columns.

mydf[!sapply(mydf, function(x) all(x == ""))]
#   A B E
# 1 a y  
# 2 b   z

---

Alternatively, as recommended by @Roland:

> mydf[, colSums(mydf != "") != 0]
  A B E
1 a y  
2 b   z