Possible Duplicate:
R - remove rows with NAs in data.frame
How can I quickly remove "rows" in a dataframe with a NA value in one of the columns?
So
     x1  x2
[1,]  1 100
[2,]  2  NA
[3,]  3 300
[4,] NA 400
[5,]  5 500
should result in:
     x1  x2
[1,]  1 100
[3,]  3 300
[5,]  5 500
 
     
    