Determine the number of rows with NAs

Question

I have a data frame as follows:

     col1   col2    col3
 1    23    17      NA
 2    55    NA      NA
 3    24    12      13
 4    34    23      12

Answer 1

DF <- read.table(text="     col1   col2    col3
 1    23    17      NA
 2    55    NA      NA
 3    24    12      13
 4    34    23      12", header=TRUE)

This gives the number of rows that contain any NA values in column 2 or 3:

sum(colSums(is.na(DF[,2:3])) > 0)
[1] 2