r - Remove columns with zero values from a dataframe

Question

I have a data.frame:

SelectVar
     a   b  c   d   e   f   g   h   i j k l ll m n o p  q   r
1 Dxa8 Dxa8 0 Dxa8 Dxa8 0 Dxa8 Dxa8 0 0 0 0  0 0 0 0 0 Dxc8 0
2 Dxb8 Dxc8 0 Dxe8 Dxi8 0 tneg tpos 0 0 0 0  0 0 0 0 0 Dxi8 0

I would like to remove the columns with zero values in both rows from the data frame, so it yields a data frame as below:

SelectVar
     a   b    d    e    g   h     q   
1 Dxa8 Dxa8 Dxa8 Dxa8 Dxa8 Dxa8  Dxc8 
2 Dxb8 Dxc8 Dxe8 Dxi8 tneg tpos  Dxi8 

Have tried:

SelectVar!=0

which yields a True/False dataframe, and:

SelectVar[, colSums(abs(SelectVar)) ! == 0]

which yields an error.

How could I remove the columns with zero values in each row?

Answer 1

You almost have it. Put those two together:

 SelectVar[, colSums(SelectVar != 0) > 0]

This works because the factor columns are evaluated as numerics that are >= 1.