Question

I have a numeric matrix with 15000 columns. I want to completely remove the columns where all values are 0.

     col1     col2     col3     col4
row1  1        0        0        1
row2  3.4      0        0        2.4
row3  0.56     0        0        0
row4  0        0        0        0
 

Here I want to delete columns col2 and col3, and keep the rest.
How can I do it with R?
Thanks

Answer 1

How about this, using apply and all:

M <- as.matrix(data.frame(a=runif(10),b=rep(0,10),c=runif(10),d=rep(0,10)))

M[,which(!apply(M,2,FUN = function(x){all(x == 0)}))]